I don't think Yaya will play in league matches unless there's no other choice. He will play in the League Cup or in the FA Cup though vs League 1 or Championship clubs. As for Kompany, I think Pep has no real need for him at this point. I mean look at the squad, Kolarov or Otamendi are doing a good job at center back with John Stones. This could be Kompany's last season at City.
Remember when Pep took over Barca? He got rid of Yaya, Ronaldinho and then Etoo. I think he is also slowly revamping City by removing its influential players. Hart is the first to go, Kompany next then Yaya.
Mourinho should follow this too by removing Rooney, Carrick then Smalling.
I like your explanation, but I dont think what Pep doing in City could be a success way too for Mourinho if he follow the method. So far, Pep succeed to maximize the performance of Kolarov, De Bruyne, Iheanacho, and especially Sterling who didnt play well in last season. Like I said before, most of Premier League coaches have known Mourinho's strategy, thats why Chelsea failed last season. So Mou has to seek a new formation to get out of this hard situation. Mou once to make Casillas sat on the bench in Real Madrid, and it has been proven that the decision didnt give good impact for the team performance. So, I'm pretty sure it will give the same result if he remove Rooney.
I think he is in a dilemma then. If he doesn't bench Rooney then United will have a slow, uncreative attacking midfielder. There was a good reason why Sir Alex tried to sell him in his final year at United. Maybe LVG had the right idea when he played Rooney deeper in the center midfield. Rooney's passing is still ok, and I guess he could still defend well. It's his pace and his creativity are what's gone.
What do you think of this line up?
Ibra
Rashford ------------------------------------ Pogba ----------------------------------- Miki
Rooney (or Carrick) ------------------ Schneiderlin (or Fellaini)
Shaw ----------------------- Smalling (or Blind) ------------------- Bailly ------------------ Valencia
DDG
You got three creative players behind Ibra. And Rashford can drift up front when Ibra moves down. Also with Pogba it's the same, he can move up with Ibra as an attacking threat, then Miki can drift in the middle behind him with Valencia taking the wide position in the attack.
Pogba was also used as an attacking midfielder at Juventus with great success. Mourinho should find a way to use him well.