Of those, Ostlund is probably of the least value today since he's barely played in Rochester due to an as yet undisclosed UBI. He's just back and hasn't been on for much. Rosen is interesting in that he is way more selfish with shooting when Kulich is not around. He tried really hard to set his friend up during Kulich's time back in Rochester early in the season which is both cool and occasionally frustrating. I would hope they don't think they can shuffle Rosen up to replace Zucker next year - they need to either look at keeping Zucker for another year or another (hopefully effective) veteran winger.
I'm not sure Cozens is replaceable by Kulich at this point. But it's fascinating to have a relatively young trio helping to carry the team unexpectedly, which is oddly familiar to Quinn-Cozens-Peterka a couple years ago.
In the meantime, Kulich looks like he's taken the coaching on how to contest pucks and get into -- and more importantly stay -- in high danger areas. The fly-bys are so few compared to earlier in his pro career. Same with his back pressure pursuit when he's lost the puck. For a kid who is only 20, it's impressive to see his growth.