At the start of each season, clubs should name a squad of, say, 30 players that they will use in every competition which they play in, bit like naming your international squad before the World Cup. For the great majority of clubs, the same players are going to be named in every competition squad, but the PL clubs have the depth to name different squads for every competition if they so wish.
Firstly, that gives the fans of opposition clubs the knowledge that they may or definitely won't see the "A list" stars should they be drawn against a club and secondly, it would stop clubs playing weaker squads until they reach the semis and the final, when the big boys get trundled out to win a medal when the spade work was done by others who ultimately get nothing for their endeavours.