The club and situation he was brought into didn't help. He had some issues at Dortmund that United just let get worse.
When you sign a player for 72m on a big wage and chased him the season before you expect to play and have a plan for you. First see if the player wants to play RW, when he arrives for that price and wage you play him constantly, I think if even if he favoured the left, he played on the right a lot and would've expected to be used there. If you know about his small motivational issue at Dortmund at times, you play him, you don't try to slowly ease him here or there which Ole did while he loses fitness and focus, players like him get stuck in a rut. We also signed Ronaldo late that summer and he called out the players which caused a rift, and Cavani didn't like it either. Our season under Ole collapses and Ralf comes in.
ETH is brought in and instead of the club saying we have a 72m player on 300k, can you use him, we buy a 85m player from Ajax we value at 25m. If you're Sancho must think what the hell is going on and become very disillusioned, Rashford has the left spot and ETH has one of his former players which he'll favour and almost forced to use as the club paid a stupid amount. Antony went 12 months without doing anything, we had reports of players moaning over underperforming favourites. This was huge damage, we could've gone back for Antony the next summer if Sancho didn't work out and I understand ETH wanting some players he trusts but we also have a player 300k costing 72m from the previous summer. What club spends 72m and 85m for one possible position, maybe multiple league/CL winners drunk on money.
Sancho is a spare wheel at the club just left to fester and get slated. Rashford was playing very well and lookign happy under ETH for 6 months but I think once his friend never really got a chance, sent to Holland for training and called out for being lazy is a line crossed and Rashford started to phone it in and the whole situation becomes toxic again like it did with Rashford under Ole/Rangnick season. There's been too much mishandling, players getting slated and certain players lose the desire to play for the manager and sections of fans. Lukaku also didn't like it here, felt he got too much stick and many more.
I totally get those views of Sancho was given chances etc. The pressure is huge, even going back to players like Alan Brazil he felt it. Off the back of Fergie the expectations are immense, players and managers buckle and go defensive to trying to hang on when the opposite is required.
We had another issue bringing in Sanchez, lots of fans thought he'd play right like at Barca, yet he starts on the left on 400k over Rashford/Martial and did poorly and upset players.