Okay, if we don't buy one of the top class midfielders then we go down to the next tier of players who are around 23 years old, very good but with potential to improve. Pjanic, koke, carvalho, rakitic, bender, etc. There are literally loads of players we should have bought to improve the midfield before we went for Fellaini. You say his problem is that he isn't one of the above doesn't really matter. He's playing decently for his standards, but that's still not Manchester United standard. Would he get in any other midfield in a top team? No chance. Look at bayern, Dortmund, Barca, Madrid, atletico, juventus, Roma, city, arsenal, Chelsea, Liverpool, even spurs ffs. Fellaini wouldn't get in any of their teams. As squad player, yes for some of them, but never as a starter. That's his problem. Just isn't good enough, no shame in that.
So you're trying to tell me that he's good on the ball and is quick and agile? That's what I meant. It's a basic requirement for being a midfielder at a top team and he comes up short.
Also, them having a 3 man midfield doesn't make all the difference. How did we absolutely piss all over Liverpool every time we play them the last few years when we had midfields of jones and giggs, Carrick and scholes, or Carrick and cleverley? It's about the willingness to make runs and open yourself up. Half the time when our defenders have the ball, they have nobody to lay the ball off to because fellaini is running up the pitch to knock down a hoof or is standing out wide for whatever reason. He's not opening himself up to receive a short pass.