Like it said in my post, the board?
Both were massive marketing signings, Pogba signing was an indication that a future BdR candidate was willing to go to a poor United lacking even Champions League's, and also was a good partner to the Adidas sponsorship as he's adidas's current main man for years to come. Sanchez increased our reach in the south american market massively as well and was considered a great player throughout the league, on top of being a 'steal' away from City.
The way the club has been run in regards to signings is majority of the problem, its not a wonder why two good if not great coaches have looked awful with us (LvG and Mourinho). IF mourinho went to some where like PSG he would probably be a success, it's too late for him here at this point but the way our board goes about signings and conducting business is just as toxic and a joke.
Majority of our signings which should've been good since Gill and Fergie left have been awful, let alone disappointing.