After having time to reflect, I'll tell you why we lost this series starting from most important to least:
1. Our core are entitled, immature, and self-serving. Marner signing that ridiculous contract without earning it, Matthews not using his size and skill early in games to will this series in our favour, etc.
2. Playing Sandin over Dermott to begin the series. Sandin hardly played any hockey all season and he's inserted directly into the starting lineup. Cost us 4 important goals in all.
3. Powerplay was clueless. Part falls on the players, most falls on the coaches
4. Low IQ plays at critical times. Galchenyuk pass at the blueline, Dermott stopping and losing the puck, etc.
5. Puck luck. It's a game of inches, and we were inches away from scoring in Game 6 overtime when we dominated
6. Injuries to key players. Tavares out first game, Muzzin out for key game 7
7. Campbell allowed questionable goals whether he couldn't cover pucks in crease, allowing long shots to beat him.
8. No shows from grit players like Simmonds, Thornton, Foligno, Hyman.
Some of this is just part of sport, some speaks to the character of the team, but alot falls on the coaching and management of this team.