Well, the simplest answer is, "do they win?". If Maurice gets this team to win consistently and perform well in the playoffs, then we'll need to try to analyze how he's contributed to that. Conversely, if they don't become a winner with all this young talent, then we can look at his specific coaching deficits.
From a less generic perspective, here are some of the concerns I have had...
1) Roster composition and usage - I have had big concerns that Maurice has a tendency to fall back on vets and grinders who he can evaluate clearly in terms of them following the X's and O's set out by the coaches, with the addition of "gritty" team-oriented plays (hits, blocks, fights, etc.). His over-use of Stuart and Harrison on D, and Thorbs and others up front are "Exhibit A". Some of my concerns have been blunted somewhat since the Jets have jettisoned Stuart, Thorbs, Peluso and gone with a line-up that has players like Petan and Dano on the bottom line. However, I still have concerns that he "slots" players into roles excessively. Maybe I'm wrong and that's a rational approach, given the various skillsets and game situations, but this is an area of concern. I also think that Maurice tends to overplay his top players, which can wear them out. I think it's partly a lack of confidence in some of his younger players, but he'll need to balance this out.
2) Playing style - Maurice had considerable success coaching a high-pressure, straight line style with the Jets in 2014/15. The Jets focused more on dumping and puck pursuit and pressure, rather than on controlled zone entries, creativity in their play, etc. I think that the current version plays a style that is more creative, but it tends to lack structure, so the Jets can end up getting into trouble against more structured teams (especially if they are quick). I have also had concerns with the Jets really porous D zone coverage. Some of that might be on the players, but it's been a problem. However, I have seen some positive signs in the past 3 games. The Jets were very good at covering danger areas and mopping up loose pucks in the cylinder out from their goal.
3) Discipline / effort / training - I have been critical that Maurice over-trains his team, and this hurts them early in the season. I think it's part of an old-style discipline, that also includes being a bit softer on vets than younger players. I do think that the team gives a good effort most nights and clearly isn't anywhere close to quitting on Maurice, which is a good sign. The Jets lack of discipline with penalties is a huge issue, and I'm not sure how much of that is coaching, and how much is just the character of his core of players. This season, it's been the same vets that have been the problem (Wheeler, Buff, Perreault, Trouba). The young players actually tend to be playing with reasonable control.
4) Goalie usage - I think Maurice was horrendous in his handling of Hellebuyck last season. Pulling him 5 times probably contributed to undermining his confidence. Thankfully, Hellebuyck seems to be pretty solid this season, so perhaps not lasting damage. But I really didn't like how Maurice managed young goalies.
Anyway, that's a short list.
