I'll ignore the needlessly condescending tone to try and keep this productive.
You don't think the differences in work ethic and commitment that are obvious in game situations also impact practices and workouts? So we're supposed to believe that someone like Kane is working his ass off on the practice drills, huh? It's interesting that you acknowledge that some players will burn more calories during a game because of how they play, but seem to think that it doesn't translate to non-game situations. Seems like a ridiculous claim to make when laid out like that. So when comparing a player who approaches the overall game in a more casual way vs a player who gives maximum effort in all situations, yes I would expect there to be a meaningful difference in calories burned over the course of a season. Odds are, the player giving it his all in games is also giving it his all in practices and workouts, whereas the one who glides and doesn't show intensity unless a scoring chance presents itself is probably doing the same in practices too.
That's not even getting into the fact that the 82 games they play are by far the most intensive physical activity they do during the season. Resistance training burns relatively few calories and practices are generally far less intense than a game situation. The primary purpose of practice isn't conditioning, it's working on skills and systems. They're not trying to wear down their players so that their bodies are exhausted come game time, losing streak practices under Tortorella notwithstanding. The games are where the bulk of calories are burned during the season.
I think you've got it backwards on Zetterberg. His back issues meant he was not able to keep up the maintenance in-season, because his body couldn't handle both playing at a top level and training at a top level. So playing games at a top level took precedence, and the training suffered. Zetterberg getting the day off on practice days, or using customized workouts to work around his limitations, was a common occurrence later in his career. So his season was overwhelmingly cardio from games, hence the extreme weight loss, which just reinforces the fact that games are where the majority of (non-rest) calories are burned. If he could have kept up a typical resistance training regimen in-season, it would have minimized muscle loss.
And yes, metabolism plays a role, obviously. But we don't exactly have access to the metabolism levels of NHL players, do we? So I'm not going to speak on that because it would be baseless speculation, I can only speak to the factors we do have supporting information on. And besides, metabolism is a minimal factor when talking about professional athletes. Michael Phelps was not eating 10,000 calories a day because he had a high metabolism, he was eating that much because he was burning that much in physical activity. These are professional athletes, they are all eating a lot of food and burning a lot of calories. Their food intake and activity levels are far more important factors than their individual metabolisms.
Bringing this back to Mazur, if he is able to start the season at a reasonable weight, and maintain a proper resistance training regimen in-season, then I don't think weight loss will affect him negatively. At least no more than it affects all of the other players who are in the same situation.
