The thing is...he's not really "soft" particularly. At least, when he's "on" and playing engaged hockey up to his ability level, he's certainly not "soft". He's actually pretty gritty, fiery, competitive. The problem is...when he's "off" he does play far more passively, and a more disengaged, "soft" sort of game.
That's what makes it seem like pretty clearly a mental hurdle for him. When he's obviously capable of playing a grittier, engaged game. He just doesn't always do it. The only other element to that, is that maybe his body just isn't really built to sustain that level of gritty, competitive, engaged play, over the duration of an entirely way too long season. But it feels far more like just a conscious, mental issue...than a really "soft" style of play as a fixture of his game.