I think you are hitting the nail on the head, Kip. Plus, the timing of his injury had to put a cramp on the development curve. How many games did he miss? Plus, how long did it take him to get to full game conditioning one he was playing? He basically lost all he'd gained from the prospects camp, etc. and then some. I think he will be fine once he gets over the curve you mentioned. Plus, he is playing against bigger and more experienced players than he did in the Q.
I don't think we should underestimate the effect missing training camp and the start of the season can have on a player. Over the years plenty of guys - vets, star players - who get injured in pre-season take months to get back in form when they come back. Imagine you're a kid playing in your first pro season. Mantha gets a semi-mulligan from me for that.