If Poch wants him, then he must know how and why he fits into our plans. He's quick, 5ft 11 (wiki) and another poster pointed out his willingness to work hard on the pitch, track back etc. Unlike when he went to Utd, he won't be moving away as such, he's a London boy.
Perhaps the main reason the transfer could happen is that Zaha might understand that he'd be signing as a squad option and is happy with that situation. I think he has potential to be a player who makes an impact from the bench and maybe earn a starting spot if he really excels. People point to Lennon and Townsend, but Lennon was sold because he didn't have the right attitude for Poch. Townsend was sold possibly in part to attitude (row with staff) but also because he wasn't happy at just being a squad option. It wasn't strictly footballing reasons Poch got rid, especially in the case of Lennon.
If Zaha signs and applies himself, I think he'd be a very useful player for us. We certainly need the option of pace in our attack and that'd help a lot with being able to play on the counter when we have a solid lead in a game, or where we are on the back-foot against a stronger side (Champions League, tough away Premier League games).