We all like to think of teams as "a club" where the manager is like a scout master overseeing a bunch of friendly cubs. Reality is that CCFC, in common with every other team, is a hard-headed business where, unless you are likely to deliver the goods for the next game, you are surplus and always going to be binned off despite whatever contribution you have made previously. That's sentimentally sad but is 100% how it should be in a results-focused business.
Fergie was the ultimate hard-head in this regard; dropping the likes of Jim Leighton for the 1990 cup final replay, Bryan Robson (club legend) for the 1994 FA Cup final and Steve Bruce (another club legend) for the 1996 FA Cup final was purely for tactical reasons - United won all three games with Les Sealey, Roy Keane and David May, respectively, having good games in the places of those dropped.
The only thing that's important is the advancement of the team on the pitch and each player is expendable and replaceable once there is someone else in their position who can offer more than them.