It's true, Butler has played under a different coach in a different system most of his career. Thibs is a very different coach than Stotts. On that, we agree 100%.
Last year in MIN he wasn't really the #1 option. Wiggins actually averaged a faction more FGA/G and KAT was a very close third. For all practical purposes, in their system, they were 1a, 1b and 1c and whose number was called varied depending on match ups and situations. All three had comparable USG% rates (as did also Jamal Crawford), but Butler averaged significantly more assists than the others (and keep in mind, that an assists counts as a "used" possession) .
And that's what impresses me the most about Butler, he uses possessions very efficiently. It's been pointed out that he "only" averages 1 more ppg than C.J., but he does so on 3 fewer FGA/G while also handing out and additional 1.5 more apg. And, that's just the offensive end. When you also include Butler's defense, he would be a very significant upgrade over C.J. at both ends.
As far as playing under a different coach in a different system, Butler's last year in CHI, he played under Fred Hoiberg, whose coaching style/philosophy is more similar to Stotts than Thibs. Under Hoiberg, Butler had a career year, posting career highs in most offensive categories (ppg, rpg, apg, PER, TS% made 3FG, etc.).
I think Butler paired with Dame and Nurk gives us a much more balanced Big 3 than we currently have with Dame, C.J. and Nurk. It also gives us a much better defense.
I also don't believe Butler would be a 1-year rental. I think Damian Lillard is the type of focused, driven teammate Butler dreams of playing with. I think he would love playing next to Dame and would eagerly resign with POR.
And yes, Butler missed 23 games last year, but he has never had a serious, career threatening injury. Thibs has a well earned reputation for playing his starters too many minutes, and that leads to fatigue related injuries. Butler has been in the top 4 in MPG for the last five seasons in a row. Cut back on his MPG and a lot of those fatigue related injuries will likely disappear.
BNM