It could be any players really, whichever examples you think of yourself. I just used De Gea and Ronaldo as examples as they're the players I don't think fit who also have a certain amount of support on the forum and in the fanbase.
My question really was whether we have the appetite for those difficult calls, whatever form they happen to take. Both from the club's POV in terms of writing-off the money they've outlayed on them and from the fans' POV in terms of accepting that players you personally like and rate could still not suit the manager even while players you don't rate do.
Especially as every time a new manager is appointed there's a tendency towards posts like:
"[new manager] is great, such an improvement on [previous manager]. You can tell just from listening to him that he's [list of adjectives that didn't apply to previous manager]. He's finally going to get rid of dross like [all the players this particular poster doesn't like]"
Whereas I don't think things get put right just by making the sort of decisions that will be almost unanimously popular in that way.