In the ui .apps module beneath /apps/wknd/components you can find the proxied teaser component. Inspect the sling:resourceSuperType property to see that it points to core/ wcm /components/teaser/v1/teaser. Also, notice the imageDelegate property. This points to wknd/components/content/image. The Teaser component will use the Image delegate to populate the image as part of the Teaser.