Tell me more about how the work of a GM is that much related to a player development
For the Habs they continue to make the same mistakes. They had 19/20 year olds that were just starting to put things together in the AHL aside from a few who started off strongly but they couldn't leave them alone to develop in the AHL for even a full season. They would call them up, the coach would bench them for little mistakes, then he would put them in the press box, then they would get sent down and they often struggled when sent down to get back to what they were doing before they were called up. Rinse, repeat several times over.
Now in no way am I saying that this is all on management or the coaching staff, the players have their own blame, the scouts as well. But the Habs clearly have had a lot of problems developing players in the last several years. They had imo one of the worst head coaches i've ever seen in the AHL. Not only did management think hiring a guy with zero head coaching experience a good idea, but after his team was one of the worst in the AHL and he made what imo was some really terrible decisions like taking your most skilled player off the top line and PP only to replace them with no talent grinders when you have the worst rated PP in the league. But that wasn't the worst part, it was re-hiring him and then even worse giving him another chance despite not getting much help from the AHL only to then finally fire him.
Clearly management has a large share of the blame for why the Habs are in the situation they are in, one of their worst seasons in the modern era, trouble developing talent, poor asset management as Timmins drafted Subban, Sergachev, McDonagh, Pac, Galchenyuk, yet management has traded them all away.