He never played any positions before joining the Sox?
Look, I'm not defending so many positional shifting, but it can become very obvious in a short time, that someone sucks at a position and would need a very long time to bring to near normal.
Maybe they felt his best chance at cracking the majors was to be a utility guy.
When you say 4 and 5 positions, it's kinda misleading when one year he played 1 games at 3B and another year 2 games in CF. That being said, there is merit saying he never really got a long look at any one position, and I think they wanted his bat so badly in the bigs that they figured his athleticism would help him improve enough to be passable. They were grossly wrong, and their prepping of him was misguided and scattered, fo sure.
IMO, I'm not sure he can be good at any position except DH.
Inning in the minors:
511 2B
440 OF
299 SS
263 1B
44 3B
That is very scattered. I'm sure it didn't help him learn one position better, but which one do you think he could be pretty good at, if he'd have been given 1800 innings at?