Regardless of his familiarity, its harder to coach at the NHL level than the AHL level and a coach, just like a player needs time to adjust their game to the increased competition. Its the reason why almost no coaches (or none) have won a Cup as a rookie. Its really hard to do right away. Blashill inherited a borderline playoff team and did just as well as his predessessor. Anybody expecting an immediate transformation was being unrealistic. Coaching a borderline team into the playoffs as a rookie coach is quite an accomplishment. He wasn't perfect, no doubt, but he did a good job considering the team is in the middle of a transition. I'd be far more disappointed with the result if he took over an established team full of prime stars and underperformed in the playoffs. He had almost the exact same season, with a very similarly transitioning team, as Dave Haskoll in Philadelphia and nobody is saying that rookie coach should be fired.
I think the Wings making the playoffs had more to do with Larkin and Mrazek having league-leading individual performances for half the season while everyone else was busy s***ting the bed. Literally every other player on the team played quantitatively worse than last year. This was a team that was on paper supposed to be better. The league-leading power play from last year now also finally had a right-handed qb in Green and a veteran player and recent Stanley cup winner in Richards. They finally got rid of Weiss. Tatar, Nyquist, Sheahan were all a year older and closer to their prime ages. And then when we had an opportunity to avenge our 7 game series loss to Tampa from last year with what should be a stronger roster, and Tampa without their top goal scorer and a top paring defenseman, the Wings managed only a single playoff victory. By all accounts this year was a disappointment and almost every player on the roster did not perform up to expectations, even if you want to factor in some sort of rookie coach handicap. Hopefully Blash has learned some things throughout the season, and uses the offseason to learn a few more things, and comes back next year in better position to get the most of this team. And hopefully he gets some help from Holland.