In comparision with Mittelstadt is Cozens a way better player and, of course, more NHL ready. Mitts had 11G+19A in 33 games in NCAA in his D+1 season, in his draft year played just couple of games in USHL - definitely he wasn't prepared enough for NHL.
Yes, Cozens hasn't soft hands like Casey has and also don't expect sick moves from him, but in every other aspect of his game he is more NHL ready than Casey was in his age.
Cozens is bigger, stronger, faster, more competitive and playing with more heart, has better shot and better physical endurance for long NHL season, also is better defensively. Instead of Casey Mittelstadt, he isn't lazy player.
If I make a choice between these two after them D+1 seasons I would take Cozens to my team all day long, he's simply different case than Casey.
Mitts also didn't look good in training camp before his rushed NHL season... so wait with Cozens until camp and if he'll show his moments then I have no problem with him to make a team next season, cause I think he should be ready in October.