Personally, I think Granato and Adams encouraging Cozens to think he could come back from his 30-goal year and be a 40 goal guy was part of it. They framed what he should focus on incorrectly IMO rather than focusing on getting better in other areas. Also, he is very good as the F1 due to his size and skating to get in on the forecheck to take the man and start contesting pucks. At center, he's caught in the area where he's supposed to be the defensive cover and when the line blows it, he appears to take it very hard. The kid is one of those who wears his heart on his sleeve. As a RW, I think he can be the player he is best at, honestly. Or if there is a winger who can be the defensive conscience for his line which honestly has never really happened. He was the eldest of the trio for a long time with Peterka and Quinn and while Quinn has also had a rollercoaster of ups and downs, their downs have coincided.
As for the fight, again, Cozens was upset at the lack of fight in the team and then reacted to Hathaway's actions and got schooled. In my mind, he's still got it in his head that too many of his teammates don't care and won't get stuck in, which could be eating him up. He seems to care, a lot, and there is not a reckoning between the players about how they do not hang together but instead hang separately. Everyone on that team who has tried to pull the team into the fray gets it beaten out of them eventually because of the lack of consistency of it. Cozens has tried. Dahlin has tried and it seems to have given him a long-standing back issue. Krebs has tried and is more of gnat than anything. But it's rarely ever been all of them at once and each has tried and then become the target for the other team and drawn back from it.
At the end of the day, I think Cozens could be a very good RW2, in the mold of how he was used by Team Canada at both the U20's and Worlds. But being good at certain things and being asked to do other things leads him to overthinking and for him, that's death with the puck on his stick.