I'm not sure taking one example is fair. I'm not even sure you can judge whether some one was "called up too early" or "damaged" as a result of it. Players go into slumps at certain points in their career. It may have had nothing to do with the call up. Many players also have extreme difficulty adjusting to MLB to start their career, even if they spent 10 years in the minors, so how can we tell if JBJ's struggles were related to not being given enough "experience" in the minors?
We can't.
Besides, JBJ played college ball and became a professional at age 21.
In 2012, he got 575 PAs at the A and AA level at age 22 after getting 40 in 2011.
In 2013, he got 374 PAs at AAA. In total, he played 218 minor league games with 989 PAs before being called up to the bigs to play 37 games. We all know he stunk at the plate that year and the next, before busting out in August of 2015.
I'm not saying he wasn't rushed, but we'll never know, if he might have needed a long adjustment period, even after more time in the minors. He was 23 when he started playing MLB.
BTW, here are some other "rushed" Sox players:
Betts: started MLB at age 21 after 298 minor league games and 1311 PAs (just 211 at AAA and 253 at AA (both less than JBJ). No college ball.
Bogaerts: started MLB at age 20 trust into a playoff role playing an off position after just 10 games of playing 3B at AAA. He played 378 games in the minors (no college ball). He played in 79 AA games (356 PAs) and just 60 games in AAA (256 PAs)- both less than JBJ.
I'm just curious why you call JBJ "the last time we called up a highly rated prospect with minimal AA and no AAA experience, and you ignored the two that worked.