I've been critical of him just based on the lack of "pop" his kicks seem to have. You watch Agauyo or any really excellent kicker, the ball just explodes off their foot. They are no doubters. Nuernberger hasn't shown that physical ability yet, which is what concerns me. The ball gets there, but not with authority. His kicks, including XP's, have a rather low trajectory. It's like he has to really punch it out there to get the force necessary to carry the ball, which might affect his accuracy some.
Obviously with more experience and confidence his misses will decrease. I guess I'm just more concerned with his physical ceiling.
I think it's fair to analyze players and provide criticism so long as it's not spiteful and petty.