You don't bring a team from league one to the championship to the PL in consecutive seasons by being a bad manager and coach. The team are just nowhere near PL quality.
And a bit like Burnley last season and Southampton this season, they're trying to play a brand of football that's probably beyond the capability of the players at this level.
I hope he doesn't get the sack but it's happened so many times that a manager does a great job getting a team promoted, then gets the sack when they inevitably stink the joint out the following season. It's almost like a punishment for overachieving the previous season!