I think you grossly underestimate Shaw. Barring a few games after injuries, he has been our most consistently good player the last two years. His positioning has vastly improved since the early days under Mourinho. One v one he is very good. Airially he is now only behind Maguire. Perhaps his biggest skill is playing out from the back, where he is our best player and the best we’ve had since Evra. And this is a highly important feature in a FB. Evra wasn’t much for ‘end product’, and struggled both in the air and 1v1 against quick wingers sometimes, but like an American footballer, he was instrumental in bringing our play from our danger zone to the oppositions danger zone with little risk. Shaw does that due to his ball controll, short passing, strength and quickness. He is not too shabby at combination play on the wing. In the opposition box he is quite useless so far.
One thing many people underestimate with Shaw, is the fact that his qualities is the reason Solskjær can allow Rashford to play like a pure forward most times, whereas AwB and others have the support of a RW with much more defensive duties. This will make Shaw look worse than he is at times, as he has to cover more ground, more runs, stand off more in attack, and in pressure play. But with a lesser LB, Rashford would not have had the season he’s had, scoring as much as our pure striker.