My problem with MN is they NEVER (sans Mauer) have recalled a player before their service time dictates it ( 5 yrs for HS). They are not quite as horrible for a college player, but close.
Talent evaluation has changed over the past decade and that's why 19yr olds like Bryce Harper & Mike Trout are recalled cause they deserve it, not due to their age. The 2 players Buxton is compared to (BJ/Justin Upton) both made their MLB debut at age 19 also. Miguel Cabrera was 20 & didnt dominate minor league ball when he came up , but their is NO shot the Twins would do the same with Miguel Sano. Basically, I believe, MN tries to develop their players for their minor league system....not their major league system.