We can go down the internal/external motivators, a screaming hard ass coach only goes so far. I've had both the warm and fuzz and the hard ass bosses, the warm and fuzzy bosses will get you middle consistency but tend to not get you elite results, the hard ass will get you elite results for a short period and will crash hard.
I dont think it is a "will" thing, I dont think the team is intentionally, consciously thinking, I'm gonna half ass it today. I think it's fear, stupidity, chasing the hero trophy, lack of confidence, self indulgent soothing behaviour, involuntary unintentional self limiting behavior, weight of the world on their shoulders behaviour. You are who you think you are. Free these guys from the ghosts of the past and they look like the 80's Oilers. Allow them to stew in their failures and they look like the 80's Leafs.