You're really forgetting some important details, Zeus. Gaara basically left Kohona a changed person after his fight with Naruto. He sensed Naruto's dark side and realized that there were other directions to go other than the one he was following. I think that was all Gaara needed, as he felt trapped into the current path he was at. It even seemed like the guy was remorseful after the battle and fucking apologized to his team. This caught them so offguard, as it seemed like completely unknown feelings for Gaara. Go ahead and rewatch those parts of ep 80 again.
I'm sure he's still emotionally scarred and unstable, and the teamup with him and Rock Lee was intentional. It will be interesting how his transformation from a villian to a good guy will be, but I guess we'll have to wait for the next few episodes. Besides, villians-turned-heros are my favorite type of characters. They bring a balance and inner conflict that is rarely seen elsewhere. Though I don't like Naruto's constant good guy motif, his rare moments of inner conflict are more human and enjoyable.
Now, about Rock Lee's battle itself, did anybody else notice that he seemed to be using Drunken Fist for defense and Dragon style for offense? Despite his name, Rock Lee doesn't seem to mimic Bruce Lee's movements and style often. He had that one kick-walking move that was all Drunken, but most of it was Dragon style, which fits with the loose and fluid movements of Drunken.
Rosalina: But you didn't.
Robert: But I DON'T.
Rosalina: You sure that's right?
Robert: I was going to HAVE told you they'd come?
Rosalina: No.
Robert: The subjunctive?
Rosalina: That's not the subjunctive.
Robert: I don't think the syntax has been invented yet.
Rosalina: It would have had to have had been.
Robert: Had to have...had...been? That can't be right.