He certainly has upside but I have brought up the fact that he hasn't done much in 3 seasons either. To his defense, he was on teams that were loaded with guards so it was hard for him to get a chance, but still if he was all that he would have got more PT. People think he's a great SF, but he's really more of a SG. He's only 6'6" and 220. Kobe is 6'6" and 210.... we don't think of him as a SF.
He has a slight chance at making the Pistons roster. I think it's smart that Detroit brought him in. They have a couple 2nd round picks who are potential back ups at SG.... that's not a recipe for winning typically. At least Williams was a former lottery pick. If he's been working hard he might have a chance to get a contract there and actually see the court since they're going to have to play someone with limited experience there anyhow. Also, Detroit is loaded at SF (Prince, Maggette, Daye, Jerebko, Singler....). That goes to show what position his more natural position is (SG).