He has improved though defensively and on the boards.
I don't know, he was actually a pretty good defender for Minn, but they were overall a terrible team defensively.
Rebounding - rookie year 4.6 rpg, career 4.4 rpg, this year 4.5 rpg. He's been an OK rebounder. Part of the reason his big back to back rebounding games in the finals were a big deal is because it was unprecedented for him.
Wiggins is a very good player, but other than shooting better from 3, he's not all that different than he was most of his Minnesota career. He was a very good player in Minnesota, it just wasn't the right role for him. People keep talking about how Wiggins accepted his role with the Warriors. That's the type of role he's suited for and wanted to play, and that's why it didn't work in Minnesota. Other than the year when Butler was there, which he happened to put up numbers shockingly similar to this year, he was always needed to be the go-to guy, and it's just not him.
I really like Wiggins, and he's still got plenty of prime left. As a Minnesota fan I always liked him, but it seems clear he's much better being a very good, but not elite scorer that can defend. In the end, the reset was probably best for GS of course, but I think Minnesota as well. Not because Russell is better (he's not), but if Wiggins is in Minnesota I doubt they draft Edwards, who is the lead wing Minnesota desperately needed.