That's completely backwards for the players referenced. Players in A ball are usually just learning to get through a full professional season. There is also the need for players to face teams multiple times to learn how teams adjust against them. Shifting guys around can prevent adjustments from being made. A good college guy like Rooker can blow through it (and often do), but a hs/international guy needs that time and reps. The elite, elite hs/international guys (like Buxton) might conquer low a and high a in a full season, but that is incredibly fast moving. AAA is a holding tank for major league depth, especially on the position player side. If they have mastered AA, there is little to learn in AAA that can't be learned in the majors.