Honestly, no matter how good the coach's reach and club's lack of good players, it still nothing because the coach cannot join them playing the game during match day. The only work of the coach is for him to provide the good players and make sure his players always perform better in every match. Barcelona performance is a little low at the end of this. In this case, we cannot compare their performance with real Madrid performance because real Madrid is far stronger than Barcelona if their coach can look over them and do screening against some players so that he can sign better players that will make the team stronger back.
The point is teamwork and chemistry because that can be a good advantage if the club cannot bring in the expected players.
A good coach can do that and it is undeniable that some dark horse clubs like Sociedad or maybe Girona in the last season they did not have the resources that made it possible to be and compete very well in La Liga but they could prove that they were able to do that with makeshift players.
That indicates that sometimes players with big names alone cannot be a benchmark that a club will be successful but when there is good chemistry then indirectly their performance will also be lifted which is clear that teamwork and chemistry between coaches and players must be a priority.