I dont see how Gomes and Deng are playing nontraditional roles. True, Gomes might be a little undersized, but he is and always was a PF. I dont know how you've come up with Deng, since nothing makes me believe he isn't a SF.
You're right on Diaw though, he would've been a SF on every I know. He reminds me a lot of the young Scottie Pippen, his defense has room for improvement as has his shot, but his game is a lot like Pippen's was in his early days. I believe, once Amare is back, he will move back to the traditional SF position, maybe sharing PF duties with Marion. And actually, that is where I think he should play.