diff --git a/api/builtins/NamespaceTransformer.go b/api/builtins/NamespaceTransformer.go
index 22937055c..8f7fddec8 100644
--- a/api/builtins/NamespaceTransformer.go
+++ b/api/builtins/NamespaceTransformer.go
@@ -5,13 +5,11 @@ package builtins
 
 import (
 	"fmt"
-	"strings"
 
 	"sigs.k8s.io/kustomize/api/filters/namespace"
 	"sigs.k8s.io/kustomize/api/resid"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/resource"
-	"sigs.k8s.io/kustomize/api/transform"
 	"sigs.k8s.io/kustomize/api/types"
 	"sigs.k8s.io/kustomize/kyaml/filtersutil"
 	"sigs.k8s.io/yaml"
@@ -21,22 +19,12 @@ import (
 type NamespaceTransformerPlugin struct {
 	types.ObjectMeta `json:"metadata,omitempty" yaml:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"`
 	FieldSpecs       []types.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
-
-	// YAMLSupport can be set to true to use the kyaml filter instead of the
-	// kunstruct transformer.
-	// TODO: change the default to use kyaml when it is stable
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 func (p *NamespaceTransformerPlugin) Config(
 	_ *resmap.PluginHelpers, c []byte) (err error) {
 	p.Namespace = ""
 	p.FieldSpecs = nil
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	return yaml.Unmarshal(c, p)
 }
 
@@ -49,31 +37,13 @@ func (p *NamespaceTransformerPlugin) Transform(m resmap.ResMap) error {
 			// Don't mutate empty objects?
 			continue
 		}
-
-		id := r.OrgId()
-
-		if p.YAMLSupport {
-			// use the new style transform
-			err := filtersutil.ApplyToJSON(namespace.Filter{
-				Namespace: p.Namespace,
-				FsSlice:   p.FieldSpecs,
-			}, r)
-			if err != nil {
-				return err
-			}
-		} else {
-			// use the old style transform
-			applicableFs := p.applicableFieldSpecs(id)
-			for _, fs := range applicableFs {
-				err := transform.MutateField(
-					r.Map(), fs.PathSlice(), fs.CreateIfNotPresent,
-					p.changeNamespace(r))
-				if err != nil {
-					return err
-				}
-			}
+		err := filtersutil.ApplyToJSON(namespace.Filter{
+			Namespace: p.Namespace,
+			FsSlice:   p.FieldSpecs,
+		}, r)
+		if err != nil {
+			return err
 		}
-
 		matches := m.GetMatchingResourcesByCurrentId(r.CurId().Equals)
 		if len(matches) != 1 {
 			return fmt.Errorf(
diff --git a/api/builtins/PatchJson6902Transformer.go b/api/builtins/PatchJson6902Transformer.go
index 7a4535410..7d56a15f3 100644
--- a/api/builtins/PatchJson6902Transformer.go
+++ b/api/builtins/PatchJson6902Transformer.go
@@ -5,7 +5,6 @@ package builtins
 
 import (
 	"fmt"
-	"strings"
 
 	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/pkg/errors"
@@ -24,8 +23,6 @@ type PatchJson6902TransformerPlugin struct {
 	Target       types.PatchTarget `json:"target,omitempty" yaml:"target,omitempty"`
 	Path         string            `json:"path,omitempty" yaml:"path,omitempty"`
 	JsonOp       string            `json:"jsonOp,omitempty" yaml:"jsonOp,omitempty"`
-
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 func (p *PatchJson6902TransformerPlugin) Config(
@@ -35,11 +32,6 @@ func (p *PatchJson6902TransformerPlugin) Config(
 	if err != nil {
 		return err
 	}
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	if p.Target.Name == "" {
 		return fmt.Errorf("must specify the target name")
 	}
@@ -93,22 +85,9 @@ func (p *PatchJson6902TransformerPlugin) Transform(m resmap.ResMap) error {
 	if err != nil {
 		return err
 	}
-	if !p.YAMLSupport {
-		rawObj, err := obj.MarshalJSON()
-		if err != nil {
-			return err
-		}
-		modifiedObj, err := p.decodedPatch.Apply(rawObj)
-		if err != nil {
-			return errors.Wrapf(
-				err, "failed to apply json patch '%s'", p.JsonOp)
-		}
-		return obj.UnmarshalJSON(modifiedObj)
-	} else {
-		return filtersutil.ApplyToJSON(patchjson6902.Filter{
-			Patch: p.JsonOp,
-		}, obj)
-	}
+	return filtersutil.ApplyToJSON(patchjson6902.Filter{
+		Patch: p.JsonOp,
+	}, obj)
 }
 
 func NewPatchJson6902TransformerPlugin() resmap.TransformerPlugin {
diff --git a/api/builtins/PatchStrategicMergeTransformer.go b/api/builtins/PatchStrategicMergeTransformer.go
index 0ad21cb88..e7636a71e 100644
--- a/api/builtins/PatchStrategicMergeTransformer.go
+++ b/api/builtins/PatchStrategicMergeTransformer.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/api/filters/patchstrategicmerge"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/resource"
@@ -20,8 +21,6 @@ type PatchStrategicMergeTransformerPlugin struct {
 	loadedPatches []*resource.Resource
 	Paths         []types.PatchStrategicMerge `json:"paths,omitempty" yaml:"paths,omitempty"`
 	Patches       string                      `json:"patches,omitempty" yaml:"patches,omitempty"`
-
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 func (p *PatchStrategicMergeTransformerPlugin) Config(
@@ -31,11 +30,6 @@ func (p *PatchStrategicMergeTransformerPlugin) Config(
 	if err != nil {
 		return err
 	}
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	if len(p.Paths) == 0 && p.Patches == "" {
 		return fmt.Errorf("empty file path and empty patch content")
 	}
@@ -79,24 +73,34 @@ func (p *PatchStrategicMergeTransformerPlugin) Transform(m resmap.ResMap) error
 		if err != nil {
 			return err
 		}
-		if !p.YAMLSupport {
-			err = target.Patch(patch.Copy())
-		} else {
-			patchCopy := patch.DeepCopy()
-			patchCopy.SetName(target.GetName())
-			patchCopy.SetNamespace(target.GetNamespace())
-			patchCopy.SetGvk(target.GetGvk())
-			node, err := filtersutil.GetRNode(patchCopy)
-			if err != nil {
-				return err
-			}
-			err = filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
-				Patch: node,
-			}, target)
-		}
+		patchCopy := patch.DeepCopy()
+		patchCopy.SetName(target.GetName())
+		patchCopy.SetNamespace(target.GetNamespace())
+		patchCopy.SetGvk(target.GetGvk())
+		node, err := filtersutil.GetRNode(patchCopy)
 		if err != nil {
 			return err
 		}
+		err = filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
+			Patch: node,
+		}, target)
+		if err != nil {
+			// Check for an error string from UnmarshalJSON that's indicative
+			// of an object that's missing basic KRM fields, and thus may have been
+			// entirely deleted (an acceptable outcome).  This error handling should
+			// be deleted along with use of ResMap and apimachinery functions like
+			// UnmarshalJSON.
+			if !strings.Contains(err.Error(), "Object 'Kind' is missing") {
+				// Some unknown error, let it through.
+				return err
+			}
+			if len(target.Map()) != 0 {
+				return errors.Wrapf(
+					err, "with unexpectedly non-empty object map of size %d",
+					len(target.Map()))
+			}
+			// Fall through to handle deleted object.
+		}
 		if len(target.Map()) == 0 {
 			// This means all fields have been removed from the object.
 			// This can happen if a patch required deletion of the
diff --git a/api/builtins/PatchTransformer.go b/api/builtins/PatchTransformer.go
index fd4651a9b..cb7a83c01 100644
--- a/api/builtins/PatchTransformer.go
+++ b/api/builtins/PatchTransformer.go
@@ -8,7 +8,6 @@ import (
 	"strings"
 
 	jsonpatch "github.com/evanphx/json-patch"
-	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/api/filters/patchjson6902"
 	"sigs.k8s.io/kustomize/api/filters/patchstrategicmerge"
 	"sigs.k8s.io/kustomize/api/resmap"
@@ -24,8 +23,6 @@ type PatchTransformerPlugin struct {
 	Path         string          `json:"path,omitempty" yaml:"path,omitempty"`
 	Patch        string          `json:"patch,omitempty" yaml:"patch,omitempty"`
 	Target       *types.Selector `json:"target,omitempty" yaml:"target,omitempty"`
-
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 func (p *PatchTransformerPlugin) Config(
@@ -34,11 +31,6 @@ func (p *PatchTransformerPlugin) Config(
 	if err != nil {
 		return err
 	}
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	p.Patch = strings.TrimSpace(p.Patch)
 	if p.Patch == "" && p.Path == "" {
 		return fmt.Errorf(
@@ -78,11 +70,11 @@ func (p *PatchTransformerPlugin) Config(
 }
 
 func (p *PatchTransformerPlugin) Transform(m resmap.ResMap) error {
-	if p.loadedPatch != nil {
+	if p.loadedPatch == nil {
+		return p.transformJson6902(m, p.decodedPatch)
+	} else {
 		// The patch was a strategic merge patch
 		return p.transformStrategicMerge(m, p.loadedPatch)
-	} else {
-		return p.transformJson6902(m, p.decodedPatch)
 	}
 }
 
@@ -116,20 +108,15 @@ func (p *PatchTransformerPlugin) transformStrategicMerge(m resmap.ResMap, patch
 }
 
 // applySMPatch applies the provided strategic merge patch to the
-// given resource. Depending on the value of YAMLSupport, it will either
-// use the legacy implementation or the kyaml-based solution.
+// given resource.
 func (p *PatchTransformerPlugin) applySMPatch(resource, patch *resource.Resource) error {
-	if !p.YAMLSupport {
-		return resource.Patch(patch.Copy())
-	} else {
-		node, err := filtersutil.GetRNode(patch)
-		if err != nil {
-			return err
-		}
-		return filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
-			Patch: node,
-		}, resource)
+	node, err := filtersutil.GetRNode(patch)
+	if err != nil {
+		return err
 	}
+	return filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
+		Patch: node,
+	}, resource)
 }
 
 // transformJson6902 applies the provided json6902 patch
@@ -138,13 +125,14 @@ func (p *PatchTransformerPlugin) transformJson6902(m resmap.ResMap, patch jsonpa
 	if p.Target == nil {
 		return fmt.Errorf("must specify a target for patch %s", p.Patch)
 	}
-
 	resources, err := m.Select(*p.Target)
 	if err != nil {
 		return err
 	}
 	for _, res := range resources {
-		err = p.applyJson6902Patch(res, patch)
+		err = filtersutil.ApplyToJSON(patchjson6902.Filter{
+			Patch: p.Patch,
+		}, res)
 		if err != nil {
 			return err
 		}
@@ -152,28 +140,6 @@ func (p *PatchTransformerPlugin) transformJson6902(m resmap.ResMap, patch jsonpa
 	return nil
 }
 
-// applyJson6902Patch applies the provided patch to the given resource.
-// Depending on the value of YAMLSupport, it will either
-// use the legacy implementation or the kyaml-based solution.
-func (p *PatchTransformerPlugin) applyJson6902Patch(resource *resource.Resource, patch jsonpatch.Patch) error {
-	if !p.YAMLSupport {
-		rawObj, err := resource.MarshalJSON()
-		if err != nil {
-			return err
-		}
-		modifiedObj, err := patch.Apply(rawObj)
-		if err != nil {
-			return errors.Wrapf(
-				err, "failed to apply json patch '%s'", p.Patch)
-		}
-		return resource.UnmarshalJSON(modifiedObj)
-	} else {
-		return filtersutil.ApplyToJSON(patchjson6902.Filter{
-			Patch: p.Patch,
-		}, resource)
-	}
-}
-
 // jsonPatchFromBytes loads a Json 6902 patch from
 // a bytes input
 func jsonPatchFromBytes(
diff --git a/api/testutils/kusttest/harnessenhanced.go b/api/testutils/kusttest/harnessenhanced.go
index 6ed84af14..f40320b0f 100644
--- a/api/testutils/kusttest/harnessenhanced.go
+++ b/api/testutils/kusttest/harnessenhanced.go
@@ -4,9 +4,6 @@
 package kusttest_test
 
 import (
-	"bytes"
-	"fmt"
-	"strconv"
 	"testing"
 
 	"sigs.k8s.io/kustomize/api/filesys"
@@ -20,8 +17,6 @@ import (
 	"sigs.k8s.io/kustomize/api/resource"
 	valtest_test "sigs.k8s.io/kustomize/api/testutils/valtest"
 	"sigs.k8s.io/kustomize/api/types"
-	"sigs.k8s.io/kustomize/kyaml/kio"
-	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
 // HarnessEnhanced manages a full plugin environment for tests.
@@ -130,42 +125,8 @@ func (th *HarnessEnhanced) LoadAndRunTransformer(
 
 func (th *HarnessEnhanced) RunTransformerAndCheckResult(
 	config, input, expected string) {
-	for _, b := range []bool{true, false} {
-		th.t.Run(fmt.Sprintf("yaml-%v", b), func(t *testing.T) {
-			c, err := toggleYamlSupportField(config, b)
-			if err != nil {
-				th.t.Fatalf("Err: %v", err)
-			}
-			resMap, err := th.RunTransformer(c, input)
-			if err != nil {
-				th.t.Fatalf("Err: %v", err)
-			}
-			th.AssertActualEqualsExpected(resMap, expected)
-		})
-	}
-}
-
-func toggleYamlSupportField(config string, yamlSupport bool) (string, error) {
-	var out bytes.Buffer
-	rw := kio.ByteReadWriter{
-		Reader: bytes.NewBufferString(config),
-		Writer: &out,
-	}
-	err := kio.Pipeline{
-		Inputs: []kio.Reader{&rw},
-		Filters: []kio.Filter{
-			kio.FilterAll(yaml.FilterFunc(
-				func(node *yaml.RNode) (*yaml.RNode, error) {
-					return node.Pipe(yaml.FieldSetter{
-						Name:        "yamlSupport",
-						StringValue: strconv.FormatBool(yamlSupport),
-					})
-				}),
-			),
-		},
-		Outputs: []kio.Writer{&rw},
-	}.Execute()
-	return out.String(), err
+	resMap := th.LoadAndRunTransformer(config, input)
+	th.AssertActualEqualsExpected(resMap, expected)
 }
 
 func (th *HarnessEnhanced) ErrorFromLoadAndRunTransformer(
@@ -178,16 +139,8 @@ type AssertFunc func(t *testing.T, err error)
 
 func (th *HarnessEnhanced) RunTransformerAndCheckError(
 	config, input string, assertFn AssertFunc) {
-	for _, b := range []bool{true, false} {
-		th.t.Run(fmt.Sprintf("yaml-%v", b), func(t *testing.T) {
-			c, err := toggleYamlSupportField(config, b)
-			if err != nil {
-				th.t.Fatalf("Err: %v", err)
-			}
-			_, err = th.RunTransformer(c, input)
-			assertFn(t, err)
-		})
-	}
+	_, err := th.RunTransformer(config, input)
+	assertFn(th.t, err)
 }
 
 func (th *HarnessEnhanced) RunTransformer(
@@ -203,6 +156,7 @@ func (th *HarnessEnhanced) RunTransformerFromResMap(
 	config string, resMap resmap.ResMap) (resmap.ResMap, error) {
 	transConfig, err := th.rf.RF().FromBytes([]byte(config))
 	if err != nil {
+		th.t.Logf("config: '%s'", config)
 		th.t.Fatalf("Err: %v", err)
 	}
 	g, err := th.pl.LoadTransformer(
diff --git a/plugin/builtin/namespacetransformer/NamespaceTransformer.go b/plugin/builtin/namespacetransformer/NamespaceTransformer.go
index 32d9c05a3..b027f50a4 100644
--- a/plugin/builtin/namespacetransformer/NamespaceTransformer.go
+++ b/plugin/builtin/namespacetransformer/NamespaceTransformer.go
@@ -6,13 +6,11 @@ package main
 
 import (
 	"fmt"
-	"strings"
 
 	"sigs.k8s.io/kustomize/api/filters/namespace"
 	"sigs.k8s.io/kustomize/api/resid"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/resource"
-	"sigs.k8s.io/kustomize/api/transform"
 	"sigs.k8s.io/kustomize/api/types"
 	"sigs.k8s.io/kustomize/kyaml/filtersutil"
 	"sigs.k8s.io/yaml"
@@ -22,11 +20,6 @@ import (
 type plugin struct {
 	types.ObjectMeta `json:"metadata,omitempty" yaml:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"`
 	FieldSpecs       []types.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
-
-	// YAMLSupport can be set to true to use the kyaml filter instead of the
-	// kunstruct transformer.
-	// TODO: change the default to use kyaml when it is stable
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 //noinspection GoUnusedGlobalVariable
@@ -36,11 +29,6 @@ func (p *plugin) Config(
 	_ *resmap.PluginHelpers, c []byte) (err error) {
 	p.Namespace = ""
 	p.FieldSpecs = nil
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	return yaml.Unmarshal(c, p)
 }
 
@@ -53,31 +41,13 @@ func (p *plugin) Transform(m resmap.ResMap) error {
 			// Don't mutate empty objects?
 			continue
 		}
-
-		id := r.OrgId()
-
-		if p.YAMLSupport {
-			// use the new style transform
-			err := filtersutil.ApplyToJSON(namespace.Filter{
-				Namespace: p.Namespace,
-				FsSlice:   p.FieldSpecs,
-			}, r)
-			if err != nil {
-				return err
-			}
-		} else {
-			// use the old style transform
-			applicableFs := p.applicableFieldSpecs(id)
-			for _, fs := range applicableFs {
-				err := transform.MutateField(
-					r.Map(), fs.PathSlice(), fs.CreateIfNotPresent,
-					p.changeNamespace(r))
-				if err != nil {
-					return err
-				}
-			}
+		err := filtersutil.ApplyToJSON(namespace.Filter{
+			Namespace: p.Namespace,
+			FsSlice:   p.FieldSpecs,
+		}, r)
+		if err != nil {
+			return err
 		}
-
 		matches := m.GetMatchingResourcesByCurrentId(r.CurId().Equals)
 		if len(matches) != 1 {
 			return fmt.Errorf(
diff --git a/plugin/builtin/patchjson6902transformer/PatchJson6902Transformer.go b/plugin/builtin/patchjson6902transformer/PatchJson6902Transformer.go
index 838a52e33..f07226fc9 100644
--- a/plugin/builtin/patchjson6902transformer/PatchJson6902Transformer.go
+++ b/plugin/builtin/patchjson6902transformer/PatchJson6902Transformer.go
@@ -6,7 +6,6 @@ package main
 
 import (
 	"fmt"
-	"strings"
 
 	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/pkg/errors"
@@ -25,8 +24,6 @@ type plugin struct {
 	Target       types.PatchTarget `json:"target,omitempty" yaml:"target,omitempty"`
 	Path         string            `json:"path,omitempty" yaml:"path,omitempty"`
 	JsonOp       string            `json:"jsonOp,omitempty" yaml:"jsonOp,omitempty"`
-
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 //noinspection GoUnusedGlobalVariable
@@ -39,11 +36,6 @@ func (p *plugin) Config(
 	if err != nil {
 		return err
 	}
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	if p.Target.Name == "" {
 		return fmt.Errorf("must specify the target name")
 	}
@@ -97,20 +89,7 @@ func (p *plugin) Transform(m resmap.ResMap) error {
 	if err != nil {
 		return err
 	}
-	if !p.YAMLSupport {
-		rawObj, err := obj.MarshalJSON()
-		if err != nil {
-			return err
-		}
-		modifiedObj, err := p.decodedPatch.Apply(rawObj)
-		if err != nil {
-			return errors.Wrapf(
-				err, "failed to apply json patch '%s'", p.JsonOp)
-		}
-		return obj.UnmarshalJSON(modifiedObj)
-	} else {
-		return filtersutil.ApplyToJSON(patchjson6902.Filter{
-			Patch: p.JsonOp,
-		}, obj)
-	}
+	return filtersutil.ApplyToJSON(patchjson6902.Filter{
+		Patch: p.JsonOp,
+	}, obj)
 }
diff --git a/plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go b/plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go
index c6b487ad0..4f61f031d 100644
--- a/plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go
+++ b/plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/api/filters/patchstrategicmerge"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/resource"
@@ -21,8 +22,6 @@ type plugin struct {
 	loadedPatches []*resource.Resource
 	Paths         []types.PatchStrategicMerge `json:"paths,omitempty" yaml:"paths,omitempty"`
 	Patches       string                      `json:"patches,omitempty" yaml:"patches,omitempty"`
-
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 //noinspection GoUnusedGlobalVariable
@@ -35,11 +34,6 @@ func (p *plugin) Config(
 	if err != nil {
 		return err
 	}
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	if len(p.Paths) == 0 && p.Patches == "" {
 		return fmt.Errorf("empty file path and empty patch content")
 	}
@@ -83,24 +77,34 @@ func (p *plugin) Transform(m resmap.ResMap) error {
 		if err != nil {
 			return err
 		}
-		if !p.YAMLSupport {
-			err = target.Patch(patch.Copy())
-		} else {
-			patchCopy := patch.DeepCopy()
-			patchCopy.SetName(target.GetName())
-			patchCopy.SetNamespace(target.GetNamespace())
-			patchCopy.SetGvk(target.GetGvk())
-			node, err := filtersutil.GetRNode(patchCopy)
-			if err != nil {
-				return err
-			}
-			err = filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
-				Patch: node,
-			}, target)
-		}
+		patchCopy := patch.DeepCopy()
+		patchCopy.SetName(target.GetName())
+		patchCopy.SetNamespace(target.GetNamespace())
+		patchCopy.SetGvk(target.GetGvk())
+		node, err := filtersutil.GetRNode(patchCopy)
 		if err != nil {
 			return err
 		}
+		err = filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
+			Patch: node,
+		}, target)
+		if err != nil {
+			// Check for an error string from UnmarshalJSON that's indicative
+			// of an object that's missing basic KRM fields, and thus may have been
+			// entirely deleted (an acceptable outcome).  This error handling should
+			// be deleted along with use of ResMap and apimachinery functions like
+			// UnmarshalJSON.
+			if !strings.Contains(err.Error(), "Object 'Kind' is missing") {
+				// Some unknown error, let it through.
+				return err
+			}
+			if len(target.Map()) != 0 {
+				return errors.Wrapf(
+					err, "with unexpectedly non-empty object map of size %d",
+					len(target.Map()))
+			}
+			// Fall through to handle deleted object.
+		}
 		if len(target.Map()) == 0 {
 			// This means all fields have been removed from the object.
 			// This can happen if a patch required deletion of the
diff --git a/plugin/builtin/patchstrategicmergetransformer/go.mod b/plugin/builtin/patchstrategicmergetransformer/go.mod
index 0ebc81b05..b9c7ec3b2 100644
--- a/plugin/builtin/patchstrategicmergetransformer/go.mod
+++ b/plugin/builtin/patchstrategicmergetransformer/go.mod
@@ -3,6 +3,7 @@ module sigs.k8s.io/kustomize/plugin/builtin/patchstrategicmergetransformer
 go 1.14
 
 require (
+	github.com/pkg/errors v0.8.1
 	sigs.k8s.io/kustomize/api v0.5.0
 	sigs.k8s.io/kustomize/kyaml v0.3.4
 	sigs.k8s.io/yaml v1.2.0
diff --git a/plugin/builtin/patchtransformer/PatchTransformer.go b/plugin/builtin/patchtransformer/PatchTransformer.go
index 3fb225e68..c2e917492 100644
--- a/plugin/builtin/patchtransformer/PatchTransformer.go
+++ b/plugin/builtin/patchtransformer/PatchTransformer.go
@@ -9,7 +9,6 @@ import (
 	"strings"
 
 	jsonpatch "github.com/evanphx/json-patch"
-	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/api/filters/patchjson6902"
 	"sigs.k8s.io/kustomize/api/filters/patchstrategicmerge"
 	"sigs.k8s.io/kustomize/api/resmap"
@@ -25,8 +24,6 @@ type plugin struct {
 	Path         string          `json:"path,omitempty" yaml:"path,omitempty"`
 	Patch        string          `json:"patch,omitempty" yaml:"patch,omitempty"`
 	Target       *types.Selector `json:"target,omitempty" yaml:"target,omitempty"`
-
-	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 //noinspection GoUnusedGlobalVariable
@@ -38,11 +35,6 @@ func (p *plugin) Config(
 	if err != nil {
 		return err
 	}
-	if !strings.Contains(string(c), "yamlSupport") {
-		// If not explicitly denied,
-		// activate kyaml-based transformation.
-		p.YAMLSupport = true
-	}
 	p.Patch = strings.TrimSpace(p.Patch)
 	if p.Patch == "" && p.Path == "" {
 		return fmt.Errorf(
@@ -82,11 +74,11 @@ func (p *plugin) Config(
 }
 
 func (p *plugin) Transform(m resmap.ResMap) error {
-	if p.loadedPatch != nil {
+	if p.loadedPatch == nil {
+		return p.transformJson6902(m, p.decodedPatch)
+	} else {
 		// The patch was a strategic merge patch
 		return p.transformStrategicMerge(m, p.loadedPatch)
-	} else {
-		return p.transformJson6902(m, p.decodedPatch)
 	}
 }
 
@@ -120,20 +112,15 @@ func (p *plugin) transformStrategicMerge(m resmap.ResMap, patch *resource.Resour
 }
 
 // applySMPatch applies the provided strategic merge patch to the
-// given resource. Depending on the value of YAMLSupport, it will either
-// use the legacy implementation or the kyaml-based solution.
+// given resource.
 func (p *plugin) applySMPatch(resource, patch *resource.Resource) error {
-	if !p.YAMLSupport {
-		return resource.Patch(patch.Copy())
-	} else {
-		node, err := filtersutil.GetRNode(patch)
-		if err != nil {
-			return err
-		}
-		return filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
-			Patch: node,
-		}, resource)
+	node, err := filtersutil.GetRNode(patch)
+	if err != nil {
+		return err
 	}
+	return filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
+		Patch: node,
+	}, resource)
 }
 
 // transformJson6902 applies the provided json6902 patch
@@ -142,13 +129,14 @@ func (p *plugin) transformJson6902(m resmap.ResMap, patch jsonpatch.Patch) error
 	if p.Target == nil {
 		return fmt.Errorf("must specify a target for patch %s", p.Patch)
 	}
-
 	resources, err := m.Select(*p.Target)
 	if err != nil {
 		return err
 	}
 	for _, res := range resources {
-		err = p.applyJson6902Patch(res, patch)
+		err = filtersutil.ApplyToJSON(patchjson6902.Filter{
+			Patch: p.Patch,
+		}, res)
 		if err != nil {
 			return err
 		}
@@ -156,28 +144,6 @@ func (p *plugin) transformJson6902(m resmap.ResMap, patch jsonpatch.Patch) error
 	return nil
 }
 
-// applyJson6902Patch applies the provided patch to the given resource.
-// Depending on the value of YAMLSupport, it will either
-// use the legacy implementation or the kyaml-based solution.
-func (p *plugin) applyJson6902Patch(resource *resource.Resource, patch jsonpatch.Patch) error {
-	if !p.YAMLSupport {
-		rawObj, err := resource.MarshalJSON()
-		if err != nil {
-			return err
-		}
-		modifiedObj, err := patch.Apply(rawObj)
-		if err != nil {
-			return errors.Wrapf(
-				err, "failed to apply json patch '%s'", p.Patch)
-		}
-		return resource.UnmarshalJSON(modifiedObj)
-	} else {
-		return filtersutil.ApplyToJSON(patchjson6902.Filter{
-			Patch: p.Patch,
-		}, resource)
-	}
-}
-
 // jsonPatchFromBytes loads a Json 6902 patch from
 // a bytes input
 func jsonPatchFromBytes(
diff --git a/plugin/builtin/patchtransformer/PatchTransformer_test.go b/plugin/builtin/patchtransformer/PatchTransformer_test.go
index 7373f6437..eb287a991 100644
--- a/plugin/builtin/patchtransformer/PatchTransformer_test.go
+++ b/plugin/builtin/patchtransformer/PatchTransformer_test.go
@@ -4,7 +4,6 @@
 package main_test
 
 import (
-	"fmt"
 	"strings"
 	"testing"
 
@@ -278,7 +277,11 @@ spec:
 }
 
 func TestPatchTransformerSmpSidecars(t *testing.T) {
-	patch := `
+	th := kusttest_test.MakeEnhancedHarness(t).
+		PrepBuiltin("PatchTransformer")
+	defer th.Reset()
+
+	th.WriteF("patch.yaml", `
 apiVersion: apps/v1
 kind: Deployment
 metadata:
@@ -287,100 +290,23 @@ spec:
   template:
     spec:
       containers:
-        - name: istio-proxy
-          image: docker.io/istio/proxyv2
-          args:
-          - proxy
-          - sidecar
-`
+      - name: istio-proxy
+        image: docker.io/istio/proxyv2
+        args:
+        - proxy
+        - sidecar
+`)
 
-	config := `
+	rm := th.LoadAndRunTransformer(`
 apiVersion: builtin
 kind: PatchTransformer
 metadata:
   name: notImportantHere
-yamlSupport: %t
 path: patch.yaml
 target:
   name: myDeploy
-`
-
-	// The expected results with and without yamlSupport is
-	// slightly different for this test. This is because
-	// the two different implementations order the results
-	// differently.
-	testCases := []struct {
-		testName       string
-		yamlSupport    bool
-		expectedOutput string
-	}{
-		{
-			testName:    "yaml=false",
-			yamlSupport: false,
-			expectedOutput: `
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    old-label: old-value
-  name: myDeploy
-spec:
-  replica: 2
-  template:
-    metadata:
-      labels:
-        old-label: old-value
-    spec:
-      containers:
-      - args:
-        - proxy
-        - sidecar
-        image: docker.io/istio/proxyv2
-        name: istio-proxy
-      - image: nginx
-        name: nginx
----
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    new-label: new-value
-  name: yourDeploy
-spec:
-  replica: 1
-  template:
-    metadata:
-      labels:
-        new-label: new-value
-    spec:
-      containers:
-      - image: nginx:1.7.9
-        name: nginx
----
-apiVersion: apps/v1
-kind: MyKind
-metadata:
-  label:
-    old-label: old-value
-  name: myDeploy
-spec:
-  template:
-    metadata:
-      labels:
-        old-label: old-value
-    spec:
-      containers:
-      - args:
-        - proxy
-        - sidecar
-        image: docker.io/istio/proxyv2
-        name: istio-proxy
-`,
-		},
-		{
-			testName:    "yaml=true",
-			yamlSupport: true,
-			expectedOutput: `
+`, someDeploymentResources)
+	th.AssertActualEqualsExpected(rm, `
 apiVersion: apps/v1
 kind: Deployment
 metadata:
@@ -438,24 +364,7 @@ spec:
         - sidecar
         image: docker.io/istio/proxyv2
         name: istio-proxy
-`,
-		},
-	}
-
-	for i := range testCases {
-		tc := testCases[i]
-		t.Run(tc.testName, func(t *testing.T) {
-			th := kusttest_test.MakeEnhancedHarness(t).
-				PrepBuiltin("PatchTransformer")
-			defer th.Reset()
-
-			th.WriteF("patch.yaml", patch)
-
-			c := fmt.Sprintf(config, tc.yamlSupport)
-			rm := th.LoadAndRunTransformer(c, someDeploymentResources)
-			th.AssertActualEqualsExpected(rm, tc.expectedOutput)
-		})
-	}
+`)
 }
 
 func TestPatchTransformerWithInlineJson(t *testing.T) {
diff --git a/plugin/builtin/patchtransformer/go.mod b/plugin/builtin/patchtransformer/go.mod
index 4cf93d86d..4d8fb37bb 100644
--- a/plugin/builtin/patchtransformer/go.mod
+++ b/plugin/builtin/patchtransformer/go.mod
@@ -4,7 +4,6 @@ go 1.14
 
 require (
 	github.com/evanphx/json-patch v4.5.0+incompatible
-	github.com/pkg/errors v0.8.1
 	sigs.k8s.io/kustomize/api v0.5.0
 	sigs.k8s.io/kustomize/kyaml v0.3.4
 	sigs.k8s.io/yaml v1.2.0