Could he be working on a certain pitch, say a changeup?
You never know, it's a possibility. Im sure his coaches and the organization let him know what he's got to work on.
But, if they were making him throw the pitch more and trying to establish it specifically, I would imagine they would've done it at AA. Promoting him to a higher level, then telling him we're going to make you use this pitch to improve would be a very tough thing for him.
It could just be a combination of things. He's just not as sharp. He's pressing in his first couple starts. The opponents are better hitters, and are laying off some things out of the zone.
It's a good learning experience for him, whatever it is. Hopefully he closes the season strong, and we stress the change up in instructional league.