It really is hard to name a guy who’s (1) a possible upgrade on offense without losing too much D; (2) gettable for what the Cs can offer (no Js, no Rob); and (3) doesn’t have major injury issues.
My first choice would be Dejounte Murray, but he’s a cornerstone for the Spurs; they aren’t selling, at least at any price we’d pay. I would be interested in Rubio if he wasn’t coming off his 2d ACL injury on the wrong side of 30. And after that we start to talk about players who have major flaws. For this team, I think there are very likely to be moves with more upside and lower risk than moving Smart for anybody I’ve heard.