If you play them at their own game, no, that midfield wouldn't compete. If you play them differently, pressurise differently - conserve energy, only go for the ball at key moments, use Fellaini's height and strength, use Carrick's Busquets-like match reading and Fabregas as the out-ball etc then that midfield could certainly challenge. It depends on the gameplan.
It is very rare if you go out to mimic a team that you will beat them - there is far too much talk of "competing" on a midfield by midfield basis, take the game away from the midfield, make the game about what you do when you have the ball as opposed to what you do when you're chasing the ball, etc. Teams like Barcelona/Bayern aren't unbeatable, it just takes (IMO) a very bold approach that most managers - including Sir Alex in fairness - will not go for as it is not part of their teams usual game.
