Pellegrini will fine until the players turn against him. Same happened with Mancini, players turned on him and eventually it got to a point where it was easier to replace one manager then replace a good number of players.
I'm adamant the players are the problem. With respect, that squad should be walking this, regardless of the managers setup. But the manager needs to lay down the law... and to start that, he should be dropping half the first team and playing our youth players, the same youth players the club always talks up. The club itself talks the talk but does not walk the walk.