I cant be bothered to keep banging the drum, but this binary view of correct/incorrect is such an oversimplified way of looking at things.
The fact that Glasner is tinkering, shows that he is at least, open to changing things that dont work. But lets also have a bit of trust in the reasons behind the decisions.
e.g. if he played Sarr on the left against Fulham, there must have been a reason, e.g. a tactical plan (exploit a fullback that pushes forward etc) He wont have just done it for a laugh. To say its incorrect is such a binary way of looking at it. I suspect if you asked Glasner he'd offer a more articulate reason, maybe we were on the back foot more that expected so Sarr's starting position was deeper than he wanted, perhaps we had opportunities to release him but the pass wasn't executed, perhaps even if Sarr didnt perform any standout moments he's presence kept Iwobi and Tete from pushing too far forward.
Football is a way more dynamic game, then you are giving it credit for.