Not sure I really agree with that. I think the fit issues with Monroe have always been overstated.
The first two years with him on the team:
2015-16: +4.2 net rating per 100 possessions
2016-17: +6.9 net rating per 100 possessions
Playoffs: +13.1 net rating per 100 possessions
He was basically exactly as advertised for us; he was probably our 2nd or 3rd best player these past couple years. He got off to a really poor start this season though and then got hurt on top of it. And as an expiring contract, it made sense to package him for an upgrade.
The Bucks could desperately use a rebounder/defender at C, but the impact that Bledsoe can potentially make is huge. Nobody on the Bucks is very good at creating in half-court; Giannis is alright, but the rest require at minimum a ball-screen to get anything done. Bledsoe gives them a guy that can create something out of nothing. He also takes a load off Middleton; allowing him to return to more of a spot-up/curl off off-ball screens kind of role offensively and save some of his energy for defense.
On top of that, he's a gigantic upgrade athletically speaking and his presence will allow Kidd to potentially get creative with rotations. He now has 3 legitimate options as the guys that can run the 2nd unit if he staggers minutes correctly. He can throw out a small-ball lineup of Bledsoe, Brogdon, Snell, Middleton, and Giannis if he wants to get really funky (and eventually, Jabari too).
My hope is that we'll turn around and flip Delly (paying him $9 mil to be our 3rd string PG now) and Henson or Teletovic for a big man that can give us some rebounding and defense. Not saying these guys are available for that kind of package, but someone like Tristan Thompson, Nerlens Noel, maybe Bismack Biyombo...someone in that template is probably available at low-cost. I think a Delly-Henson for Tristan swap in particular could make sense for Cleveland. Henson and Delly would both be upgrades defensively and Delly could provide shooting that Rose/Wade are simply incapable of.