Almost all coaches have shortcomings and that is human nature but Pep Guardiola has the advantage of seeing the potential of players to be placed in the match. Pep Guardiola knows what the team needs so he doesn't try to do something that makes his team lose. Just look at how when he replaces a player and it is done if it is needed, not because the player made a small mistake in the match and he gives each player the trust to develop themselves to be better.
Pep Guardiola is a genius in many ways, first of all in tactics he pioneered tiki-taka and never stopped upgrading it with time, club by club from Barcelona, Bayern Munich and now Manchester City. Secondly, he has good talent and sharp vision to realize hidden skills of players so that he can test them in very new positions and enlighten their career at such strange positions. By all these things, Pep Guardiola is able to use flexible tactics for his clubs and with his players, he can use them at multiple positions but make sure to maintain good performance of a whole team.
Erik Ten Hak may be different because he often tries to change strategies and places players who are not in their position. So what happens is that it doesn't give a better effect because the players don't know what to do and maybe this is the reason why Erik Ten Hak has difficulty developing the team to be stronger.
Ten Hag is different, lack of good ideas for tactics and he is not good to use his players. It's very easy to predict players chosen by Ten Hag for a next match and what positions these players will play in a next match if they are in from 11 chosen players squad. By this, Ten Hag gives opponents in Premier League greater chances to build up their proper plans and squads to fight against Manchester United. It's not surprised to see Manchester United failed to get good results with Ten Hag last two seasons and in early matches of this season.