Martial or Sanchez aren't good players (a whole lot more than that, in fact)? Bailly isn't a centerhalf of great potential? Fred? Herrera? Dalot potentially? Matic has had a bad season, but he was very good last season, let's not forget that. Lukaku may not be my cup of tea, but he was a very good goalscorer with room for imporvement.
And let's say our recruitment has been terrible. Well, those were all players our managers wanted, which goes back to the actual issue - wrong appointments.
You're evaluating players based on their potential only. That's the problem here most are falling in. There's absolutely no guarantee any of these will develop to great players, 50-50 chance, people were drooling over Darmian in his first 3 games as well.