I'm replying you here from the Joanna thread in the Heavies because it would get lost in there lol.
I think talking about pure striking Joanna is much better than RDA. I don't think Pettis is as high level as Joanna in general terms, Joanna is much more well rounded striker than Pettis. Pettis footwork against the cage was terrible, either he was too lazy or he has no defensive footwork other than circling squared up to the cage.
He's almost purely an out-fighter, he can't strike in the pocket, he just winged punches head down and RDA beat him up. Pettis has much better kicks sure but Joanna overall standup game is way better, and she has better TDD, both when she's against the cage and vs shots in the middle of the cage.
Joanna's boxing is also sharper, her distance management and use of footwork is superior, not a lot of wasted movement.
I think Pettis is really great when he gets his stuff going but he gets pressured and then it's goodnight. I really like him and fun to watch but for me he lacks on aspects of his standup game.
Idk just my 2 cents lol.