For the Flyers it has been Morgan Frost, which makes the Torts treatment kind of funny (in a "this is really stupid" way).
Last year after the season he spoke in his exit interview about not knowing what the coaching staff expected of him; this year he frequently speaks of confidence in his postgame interviews and being "pumped up" by teammates. Which is why it's nuts that, after being one of their best players last season and leading the team in scoring in the preseason, Tortorella decided to use him as the 13th forward for the first 2.5 months of the season.
Kid produces when he plays consistent minutes with decent linemates and looks lost when he doesn't. His 200-foot game is pretty good, he is not and never has been a defensive liability. Basically every forward on the team other than Couturier makes more boneheaded mistakes with the puck or defensively than he does. So when Tortorella benches him, it's hard to discern why—and it seems to be hard for him to figure out, too. Usually it's after games when the whole team plays terribly.
So when he's getting jerked in and out of the lineup, he usually plays pretty shitty: ultra-short shifts, over-forechecking to throw hits and look engaged even though that's not his game and he's not effective when doing that. Just looks like a guy who isn't certain what the assignment is—whereas when he's gotten comfortable on a line and just been allowed to play, he's a perfectly good NHL 2C.