Have said for a very long time (well before Man U 5-5) that he would make a great left wing back.
But
I do think he should be part of a 5 rather than a flat 4 because it gives us the security and a touch more width but it's not fair to kill him after one (and really only one) match where he got toasted, by a very good winger who had his best game, same for Chester being bombed after Man City
We can be fickle sometimes but so can managers..