I don't see it either. Something happened with Studnicka's drive or killer instinct. He had it coming out of juniors and his first year, and then it seemed like his drive to play hockey just gradually disappeared. There was just no fight in him on too many nights.
Same thing happened with JFK. I'm not casting blame on either player, I think the mental aspect can be just as hard to control as the physical, maybe harder. If JFK and Studnicka had Marchand's compete level, they would both be good top six centers in the league. But they don't and that's a real factor that separates players in professional hockey.
I’m always hesitant to weigh in too much on young players with limited NHL ice time just because there’s a whole lot of posters on this board with far more knowledge than me in that department.
But sometimes I think a “bias” or just overly rosy optimism can form from following prospects for years before they hit the NHL. Even without any proof of an effective game at the highest level, it’s easy to glorify what was seen at lower levels as more transferable to the upper echelons of hockey when it often isn’t.
A couple people have tried to compare Studnicka’s slow production rate so far in the NHL to Marchand (who coincidentally you brought up here). But the compete was always evident in Marchand. The missing open nets and finishes was too, but the drive (and talent) was there as soon as Marchand got his first shot.
As you have rightly pointed out, at no point in his time with the Bruins did I really see the intensity or a desire to do whatever it took to retain his spot at the NHL level. He’s getting another shot on a weak roster and is pretty middling there too, getting scratched numerous times and putting up little in the way of points.
I have zero reason not to wish him well. But he has shown what amounts to a whole bunch of nothing after 80 or so NHL games. He doesn’t get forever to prove it. And that’s about the player and his abilities, not a bad management group, coach, etc.