Jimmy Butler is a good player, but doesn't fit the mold of what we're looking for. He's not a good shooter and needs the ball in his hands to be effective. His defense is outstanding, but that isn't exactly a weakness for us... so selling the farm for Butler would be a huge mistake... especially given the fact that he is a marginal upgrade from Bradley.
1) Good shooter? It's a little complicated, but I think there's more good news than bad. First of all, he gets to the front of the rim, a lot, and finishes. Not unrelated, he draws fouls at a healthy rate, and he's an A-plus FT shooter. As a jump shooter: he did not have a good year; the year before he shot .378 from the arc, which is excellent, but he's been up and down throughout his career, and his midrange %s were nothing to write home about.
3% is notoriously volatile; he got more defensive attention last year; and we're pretty clear that he wasn't a happy camper, complaining about his coach not coaching them "hard enough". You have to like the toughness that that shows, though throwing his coach under the bus is not too cool.
He's a high assist, low turnover player who demands double teams; he gets shots for the whole team, is unselfish, takes care of the ball. I think that if you've got guys who can shoot around him he'll flourish.
2) "...selling the farm for him would be a mistake." I agree.
3) "...marginal upgrade from Bradley" - more than marginal, I think, but my main quibble here is that their games are different. Bradley is not a closer; Butler is - he makes things happen and gets you points by creating offense (Bradley gets most of his in the flow of the offense), gets you in the penalty. As a defender, Butler can guard bigger players.
Bradley is a good fit with Butler, I think.