Last season Bayern Munich could not win the bundesliga despite the fact that they had one of the best coaches actively still coaching and they had the best striker in the world Harry Kane. Winning the league isn't about having the  best players as if the manager is average, there's nothing he can use the players to win. It's better to have an high class manager and average players as he can transform the players into superstars but when the head which is the manager is average, the players will not respect him and he will loss hold of the locker room. Some big players will feel too big to listen to the manager and he wouldn't have the experience in big games as the champions league.