diff --git a/pkg/autoscaler/aggregation/bucketing.go b/pkg/autoscaler/aggregation/bucketing.go
index 623f801e2e91..9d5f31714d97 100644
--- a/pkg/autoscaler/aggregation/bucketing.go
+++ b/pkg/autoscaler/aggregation/bucketing.go
@@ -52,14 +52,6 @@ func (t *TimedFloat64Buckets) Record(time time.Time, name string, value float64)
 	bucket.Record(name, value)
 }
 
-// Size returns the number of buckets stored.
-func (t *TimedFloat64Buckets) Size() int {
-	t.bucketsMutex.RLock()
-	defer t.bucketsMutex.RUnlock()
-
-	return len(t.buckets)
-}
-
 // ForEachBucket calls the given Accumulator function for each bucket.
 func (t *TimedFloat64Buckets) ForEachBucket(accs ...Accumulator) {
 	t.bucketsMutex.RLock()
diff --git a/pkg/autoscaler/aggregation/bucketing_test.go b/pkg/autoscaler/aggregation/bucketing_test.go
index c0223d66a479..fbf65b5634e7 100644
--- a/pkg/autoscaler/aggregation/bucketing_test.go
+++ b/pkg/autoscaler/aggregation/bucketing_test.go
@@ -85,8 +85,8 @@ func TestTimedFloat64Buckets(t *testing.T) {
 			if !cmp.Equal(tt.want, got) {
 				t.Errorf("Unexpected values (-want +got): %v", cmp.Diff(tt.want, got))
 			}
-			if got := buckets.Size(); len(tt.want) == 0 && got != 0 {
-				t.Errorf("Size() = %d, want 0", got)
+			if got := len(buckets.buckets); len(tt.want) == 0 && got != 0 {
+				t.Errorf("len(buckets) = %d, want 0", got)
 			}
 		})
 	}
diff --git a/pkg/autoscaler/collector_test.go b/pkg/autoscaler/collector_test.go
index 196a79e61894..bf86977b7645 100644
--- a/pkg/autoscaler/collector_test.go
+++ b/pkg/autoscaler/collector_test.go
@@ -118,11 +118,13 @@ func TestMetricCollectorScraper(t *testing.T) {
 
 	now := time.Now()
 	metricKey := NewMetricKey(defaultNamespace, defaultName)
+	want := 10.0
 	stat := &StatMessage{
 		Key: metricKey,
 		Stat: Stat{
-			Time:    &now,
-			PodName: "testPod",
+			Time:                      &now,
+			PodName:                   "testPod",
+			AverageConcurrentRequests: 10.0,
 		},
 	}
 	scraper := testScraper(func() (*StatMessage, error) {
@@ -133,13 +135,14 @@ func TestMetricCollectorScraper(t *testing.T) {
 	coll := NewMetricCollector(factory, logger)
 	coll.Create(ctx, defaultMetric)
 
-	var got int
+	// stable concurrency should eventually be equal to the stat.
+	var got float64
 	wait.PollImmediate(10*time.Millisecond, 1*time.Second, func() (bool, error) {
-		got = coll.collections[metricKey].buckets.Size()
-		return got > 0, nil
+		got, _, _ = coll.StableAndPanicConcurrency(metricKey)
+		return got == want, nil
 	})
-	if got < 1 {
-		t.Errorf("buckets.Size() = %v, want > 0", got)
+	if got != want {
+		t.Errorf("StableAndPanicConcurrency() = %v, want %v", got, want)
 	}
 
 	coll.Delete(ctx, defaultNamespace, defaultName)
@@ -162,7 +165,7 @@ func TestMetricCollectorRecord(t *testing.T) {
 		Time:                             &now,
 		PodName:                          "testPod",
 		AverageConcurrentRequests:        want + 10,
-		AverageProxiedConcurrentRequests: 10, // this should be subtracted from the above
+		AverageProxiedConcurrentRequests: 10, // this should be subtracted from the above.
 	}
 	scraper := testScraper(func() (*StatMessage, error) {
 		return nil, nil
@@ -173,10 +176,6 @@ func TestMetricCollectorRecord(t *testing.T) {
 	coll.Create(ctx, defaultMetric)
 	coll.Record(metricKey, stat)
 
-	if got, want := coll.collections[metricKey].buckets.Size(), 1; got != want {
-		t.Errorf("buckets.Size() = %d, want %d", got, want)
-	}
-
 	if stable, panic, _ := coll.StableAndPanicConcurrency(metricKey); stable != panic && stable != want {
 		t.Errorf("StableAndPanicConcurrency() = %v, %v; want %v (for both)", stable, panic, want)
 	}