I think you're bordering on trolling by focusing on individual words out of context in the name of picking a fight.
Gretzky's "everything" obviously did not include those "essential" things you mention because that would be a waste of his time. Those things were not "essential" to Gretzky's game just like they aren't essential for a goalie's game. The sacrifice to his offensive game that would have been required for him to make a marginal contribution to mucking in the corners and gooning it up for his teammates wouldn't be worth it. His total contribution would be decreased by wasting time in these areas. Thus, doing these things would not be consistent with "doing everything to be the best he could".
So the original statement stands.
