I think we just have to accept we're seasons off any kind of major success and a lot of these players are not as good as we think they are. Even Pogba, for as many good games he has invisible games. De Gea our best player but can't command a box despite his great shot-stopping. Martial, doesn't play enough good games in a season to justify his new wage. Not that they aren't all great players, but Pogba and martial have as many bad games as good ones. No consistency, no success.
If we don't make top 4 which is likely, I definitely think this summer is the time to let the big players move on if they want and reinvest - build from the ground up. Next season is going to be transition at best sadly so not got a lot to lose.