That jump to big league pitching is just crazy. He got in his head in a hurry. He talked after just the first couple games about how fascinated he was at how big league pitchers were attacking him. He will be totally fine. This adversity will serve him well.
This is kind of a tangent but like 4 or 5 years ago they changed AAA to use the major league ball, which has lower seams, and the average OPS in AAA increased by like .050. Before that it was easy to trust hitter performances in Norfolk because it was really hard to hit there. But since then I think it's been difficult to predict hitter performances based on minor league performance.
The flip side to this is that if you can get AAA hitters out as a pitcher then you're probably ready for the majors. And pitchers had some problems adjusting to the majors. But that of course comes at a cost.