What you're describing isn't "treatment of players"
The McDonagh trade to Nashville is actually a GREAT example of how to handle this properly, and is in stark contrast to how things went with Drury last June. The Lightning GM sat McDonagh down at the team's exit meetings and told him what was up. McDonagh had a full-NTC, and there were deals being negotiated for a few weeks but none had come to fruition yet. Brisebois had set a deadline on when he needed to have the trade done, and if it wasn't going to be done by then, McDonagh would be put on waivers. The player *knew* this. Stamkos was told by the GM he wasn't going to be re-signed before he became a free agent. Marchand was told by the GM he was going to be traded before he was traded.
Meanwhile, Goodrow didn't know he was going to be waived until he was. Trouba was still under a NMC and Drury did not let him know that he was looking to trade him, and didn't find out until the deal to Detroit was pretty far down the road. It isn't about the fact that Goodrow was put on waivers and it isn't about the fact that Drury was trying to trade Trouba. It's about the fact that Drury treated the players like nothing more than assets, instead of treating them with courtesy and respect. It doesn't matter than both players were underperforming their contracts... they still deserved at least that from Drury.
-Does it absolve Trouba of the way he handled what came next? Of course not. He's allowed to use whatever methods his contract allows to prevent a move. But if you're going to do it the way he did, you better come into the season prepared to perform. Instead, he further poisoned the room.
-Does it absolve the rest of the team from the responsibility of their poor play the rest of the year? Absolutely not. You can be upset with your boss and still do your work with pride. Maybe it would take a few weeks to get over it, but it shouldn't linger any further than that.
In other words, the original sins that lead to this season were Drury's. The rest of it? That's on the players.