hands aren't as good as Roberts, but he's faster and seems to have an easier time getting open, especially against higher-end defenses. He also makes some absolutely spectacular catches.

My other guess is that some of his frustration, which he doesn't hide very well, stems from the fact that this year is his last tryout for the NFL, so when balls are not on target, or he misses catchable balls, he sees his stats, and therefore his NFL draft prospects, taking a hit. Pure speculation on my part, but I do know he has his eye on the NFL.