I'm thinking more about the rotation than talent. He doesn't really fit with anyone because he's such a poor defender. He can barely back it with a DPOY candidate in his prime; there's no way he can make it with Diaw as the center of the second unit. So he'd have to start, and while I've always been vocal about wanting Splitter back on the bench, I wouldn't do it for Boozer. He and Duncan could have a lot of defensive issues, and Boozer's offense isn't needed with the starters. So Diaw would start and Boozer and Splitter would come off the bench. That might work if Boozer is a consistent producer, but he's been a huge flop in Chicago in regards to being a go-to player.
For $5 Million? Perhaps he'd be worth it. However, I'm not going to pretend like I like him any more than Baynes. The Spurs have a good big rotation as it is, and inserting a black hole and poor defender isn't the way to improve in the short term. Yes, it may help on days where Duncan doesn't play, but I'd rather see the Spurs use the cap space or MLE on someone else.