If we want develop players it must also be ok for them to make errors, but at the same time they shouldn‘t be completely overlooked either.
I don‘t think the sprcific errors of Mussh are really linked to RB and playing RB as player with expirience at CDM and RM and limited expirience at RWB is also not a crazy task. But overall he is doing really well and he simply is also still in the talent phase to some degree.
Adli generally is better when he can press players, he actually wins the ball quite often. If he has players coming at him he frequently struggles, these holding tasks he has to improve. In those situations he also struggles because he tends to get beaten completely if he looses the duell, good CDMs can win tactically by maybe loosing the duell but disrupting the play so much that it becomes a strategic victory.
I think double pivot could be good for Adli, LCM is pushing it in terms of athleticism, there is a big gap to the likes of Reijnders, RLC or Musah imo.
Which players get to make errors and which don't is... complicated.
I think playing Musah at RB was a mistake--I think there's a big difference between a wingback and a fullback--but I've been a Musah fan for a long time, so maybe I'm biased.
As far as Adli goes, I think the notion that he is unathletic is... a little overstated. He has to add muscle to his frame, and he is noticeably bigger than last year, but I think playing him as a CDM is... it's a waste of his talent. I think he could play in the Reijnders spot. He probably cannot play the exact same way, but, if you play him in a Modric-like role, I think he would do wonders for our play.
We've seen our shape transform when he comes on, like against Dortmund, for example. Using possession and passing as defensive tools to reduce pressure and take oxygen away from the opponents is something Pioli seldom does.
But if we're going to use him as a regista, then he needs more defensive support from one of the CMs. That being said, I don't think he's been bad defensively, and the numbers seem to bear that out.