You're right. We need players like this McKennie to rest our starters in matches against Spezia, Benevento or Crotone.
And since he's probably a player who should play for those teams, we will lose points against them and lose the scudetto.
I'd rather have Khedira in hospital than below average players on the pitch. Our starting midfield right now is Bentancur, Arthur, Rabiot. At least two of them should be on the bench of a team aspiring to win a treble. For that to happen we need to buy two starting midfielders, and we're getting a black Texan with a Scottish surname, whose Italian is probably worse than the Inglorious Basterds'.
I hate him without ever seeing him play. I refuse to watch a single youtube clip of him, because he sucks.