This is probably for another thread, but this isn't always true. In fact, there are plenty of cases where it isn't true. Sir Alex was easily the most important person at United, but you have other clubs where it isn't the case. Messi is easily more important than anyone else at Barca, and both Iniesta and Xavi are more important to them then Tito is as well. Same case with Ronaldo and a few others at Madrid. It depends entirely on the players and who the manager is IMO, doesn't make him by default the most important person at the club.