I always here a lack of plane as a knock on shorter pitchers fastballs. I was almost exactly his height and frame. When I threw a fastball it was a 4-seam fastball. It isn't smart to try to throw the pitch down low. I threw a 4-seamer higher up and it had a lot of movement. Why can't Lakins throw a 4-seamer and get movement on it? To me movement at 90mph plays higher than 94-97mph with no movement.
I'm going to guess his problems in AA is control and command though.