This is what I don't get.
Mkhi - played as a 10 in BVB and it didn't work. Had to be switched to a wide right role to get him back to his best - or to any level of competence to be fair. He's wasted as a 10. Also, his weakest part (from last season as well) was conversion. Hardly the most ringing endorsement of why he should be a 10, surely?
Mata - never been a 10 trusted by any manager, including Jose. Why exactly would that change this season? He's not a 10 cut out for the Prem, and the sooner we all accept that, the sooner we can move on to bigger and better things.
In summary, James is one of the top 2-3 players in the world for that position. I'd rather take James than any other player for that position. If we are budget-constrained and need a stop-gap for a position which needs to be one of Mata / Martial, I'd rather that were on the wings, to be honest. The absence of a 10 means that whenever we switch to a 4-2-3-1, we have either Lingard or Fellaini playing that position. That is a deal-breaker for me.