Leicester might finish above us and are definitely better run than United right now, but their players won't 'walk' into this United side. In fact, barring Chilwell and Maddison, I can't think of any who would improve us straightaway.
Every side in the PL comes with an extra gallon of gas in the tank when they have to come play against United. Also, every player in the red shirt is subject to far more scrutiny than elsewhere. The stakes are higher, your mistakes have greater impact, and your nerves will be tested.
Their Turkish CB can find it easy to move on from his errors against us because his ex-manager isn't a CL winner who comes on TV to berate him. Ayoze Perez can get away with a barren spell of no goals without scrutiny but Jesse Lingard cannot. Pogba has the same number of assists as Maddison but the forner's season is identified by a missed penalty while the latter's by his solo wonder goal.
If Leicester's starting XI were playing for United, I don't think they'd be third after 7 games.