Sorry but trusting an 18yo who has basically minuscule first-team appearances is ridiculous. There's a January transfer window too if he proves himself worthy while playing actual Premier League games. 7 players for 3 midfield spots is not overkill.Anything beyond 2 players per position is overkill, it's how we ended up with dressing room mutiny under Ole because so many players couldn't get game time.
Either Mainoo is a serious first team option or he isn't. If he's not, I agree we need another midfielder, but that must be done on the understanding Mainoo is barely getting a game all season. Mainoo got 2 appearances last year I believe and he'll do well to get more than 5 this year if we go into the season with 6 senior midfielders in front of him.
Ole's dressing room issue was more sticking with players who weren't performing and the team was doing badly. There were no such issues in his previous seasons when we finished 3rd and then 2nd.