We've already seen him play the piece of shyt heel multiple times. When he started doing the Joker thing and wearing weird clothes, it was interesting. Then he translated that to his face character and it worked well. Him being a good guy and hating/criticizing Punk is way more complex and interesting than him just flat out being a heel who hates Punk because he's supposed to.
Even now, he still does the same catchphrases and has the same entrance music. Becky leaned into everything that people hate about her and turned herself into a despicable, irritating piece of shyt that constantly has to remind people who she is. She's never played that character before, which is why it works so well.