Granlund's skating during the first few years wasn't good, but he improved a LOT after starting to focus on it more. His offseason training with figure skaters really helped a lot, especially on his edgework but also his acceleration. Proof that skating doesn't stop developing at 20, not by any means. He (and coaching staff) identified a weakness, and he put in the blood, sweat, and tears to address it. The result was a near-PPG player at his prime.
His shot was surprisingly okay, but he took too long to get it off. And in NHL, that's just a no. His game was tailor-made for international ice and European style of play, and moving to NA revealed his weaknesses. In fairness, the hockey IQ and passing ability, as well as his stickhandling was at a level where most thought the poor skating and lack of physicality wouldn't be such glaring issues.
I agree, but he still needs to improve. Rossi could really use that extra gear. But, lest we forget he lost a year (probably over that) of his development. I'd say he is only now starting to catch up to where he was projected at D+1. Definitely looks stronger now though, so that part is in a shape where he can focus on skating next. I'd like to see him work with professional in a similar capacity to Granlund, because that really worked wonders for him.