I don't know what happens inside, but I have the feeling that Mourinho never gave him a fair treatment. After the broken leg I guess the kid was insecure when he was playing, and sensitive at the minimal signal of pain. Given the situation Mourinho should have been a bit more gentle and show the lad a bit of warm. Instead of it he was thrown under the bus systematically.
It's true that when we hired LVG Shaw was sent to train aside the group because he wasn't fit. Surely the kid has some problems and needs to put in extra efforts, but after that period I remember him playing well and becoming a fix starter, performing like the best left back in the league. The talent is there but he needs an arm around the shoulder, and I'm sure that under Ferguson (or anyone with man mangement skills) he'd be flying again down the left side. Mourinho seems to be incapable of it, or maybe he doesn't even want. He only seems to be friendly with the workhorses, while the rest are ignored or treated miserably.
Now it's pointless to keep Shaw if Jose is going to remain next season, but I'd like to see the kid under a more decent manager, along with players like Pogba or Martial who don't seem to be enjoying at all. The task of the manager is to get the best out of the talents and It's obvious that Mourinho is not getting enough out of them. All he does is to ask for money and transfers, but he's got the tools at home. It's his fault that he's not interested or just incapable of squeezing the talent at his disposal.
To me this case looks like De Bruyne, Salah, Lukaku film at Chelsea, we're at risk of losing exciting talents and then regret when they shine anywhere else. I'd pay that price if Mourinho had us playing like buffalos and competing for the big trophies. But I don't think it's worth to accept Mourinho antics and negatives to win a pair of mickey mouse cups, and play the current garbage football. While he admits we had no chance at CL and cries every week about City having advantages, heritages or whatever.
I'm sure that any half decent manager with the current squad could easily replicate and improve what he's offering us, and without his antics, the dull displays and the permanent drama. If our club wasn't being ruled by ignorants Mourinho would be shown the door at the end of the season.