The entire train of illogical reasoning.
Let's go over some of your reasoning failures:
1) You're assuming that what Eric Engels wrote is an
exact description of McCarron's summer activities.
2) You use of quotation marks shows that you're assuming that a loss of ~5 lbs of fat while gaining a lot of muscle is not impressive.
3) You're assuming that if McCarron trained in the summer of 2018, then he did not train in the previous summers because he was being lazy, as opposed to the possibility that he was training on other issues, or that he got advice to train smarter.
4) You're then assuming then this makes McCarron arrogant.
5) Which you then assume is due to a sense of entitlement that he had from being a first round draft pick.
6) You're also assuming that he was given correct and specific advice from day 1.
You're making a lot of irrational and unfounded assumptions.
Here's what we actually know:
1) Eric Engels gave a brief description of McCarron's summer 2018 training program, over his Twitter account. He says that McCarron hired a skating coach this summer. He did not say that McCarron had never previously worked on his skating.
2) McCarron is a more effective skater this year.
3) Bouchard is putting McCarron in a position to succeed, rather than in a position to fail.
4) McCarron is playing more effectively, and with more confidence.
There are other possibilities for what could have happened. For example it could be that McCarron trained in previous summers, but that he was not successful. This can happen if he has an injury, or if he is given the wrong advice on how to train. It may be that McCarron had been given the wrong advice on which coach to hire, or that he's got such a peculiar body type that only a small fraction of skating coaches will be able to teach him proper technique. Sometimes people train properly, but are not immediately successful. It can also be that McCarron was training on the wrong things, for example it's possible that Lefebvre told him to focus on fighting.