Yeah but AAA pitching is better than AA. He'll get more quality at bats in AAA than AA. In other words, we'll get a better idea of what he'll be by seeing what he does in AAA. If he can maintain the OBP and power in AAA, he's probably going to be pretty good when he's 27-30.
I see that the Rangers apparently don't have a minor league affiliate in the EAS league... For the Giants prospects, AA is actually the truest test for hitters because the pitching is roughest in the EAS league for our AA affiliate in Richmond. Many Giants fans freaked out when Gary Brown and Joe Panik saw their numbers drop substantially in AA due to first-half slumps in Richmond after their excellent year in San Jose in the CAL league, but both guys had much-improved second halfs in AA, showing that they had fought through the harshness of that level which sees a lot of better pitching.
The Rangers' Round Rock AAA team is in the PCL, like the Giants AAA team the Fresno Grizzlies... But that is a league that is notoriously hitter-friendly, with many inflated numbers for hitters, and a whole way of pitching that is very different from MLB-level pitching. For instance, guys who pitch at that level, in the PCL, practically never, ever throw inside. Makes hitting a lot easier, and it's one reason why Giants pitchers have largely remained at AAA for barely a few months at most, doing most of their minor league work at low-A, A and then AA.
I don't think Olt is missing that much by not playing in AAA yet. The PCL league will almost surely just give him a bunch of great-looking numbers, which can always be useful for hitters who are on their way to MLB, but is not necessary beyond a couple of months, really. But you have affiliates in the SAL league (like we do) and one in the CAR league...
But, yeah, Perfect Poster
is right. AAA is pretty much the coronation for a budding star--you aren't going to be spending very much time there, by and large... and, otherwise, it's where retreads and never-will-bes quietly stagnate.