Fellaini's midfield partnerships have been pretty hit and miss since Arteta came back from the injury he suffered at Newcastle. When Arteta was out Fellaini hit a purple patch when he had either Osman or Pienaar partnering him in the middle of the park. Week in week out he dominated. The Fellaini/Rodwell pairing has never come close to it.
Moyes has the option to turn to Pienaar again I suppose but I suspect he brought him back to pacify Baines and shore up the left hand side. We need to see how Gibson pans out. Rodwell/Felli is not the magic bullet.
And that worked because Osman and Pienaar are creative link up players who can distribute well. Again, the problem has been creativity around him rather than the midfield itself. The reoccurring theme when Felli and Rodders played was always good possession but no cutting edge as we had no width and Cahill just in front of them.
Additionally, Fellaini has also played well with Neville or Heitinga just sitting behind him. He covers more ground than almost everyone in the team because he's up and down. That works better when he has a player sitting and covering him when he ventures. But it doesnt work so well when there's no creativity on the flanks or in front of him...which is why he's been hit and miss with Rodwell...Rodwell looking better of the two because of it.
Felli and Rodwell hardly ever lose the ball when in possession. The old "they just pass side ways" is true...but the difference now is that we have Drenthe, Donovan, and Pienaar out there so its no surprise Fellaini looks better because, even without Gibson IMO, he has better players around him who can pick him out or vice versa.
The Felli/Rodwell partnership will look twice as good with Donovan, Drenthe and Pienaar in the mix IMO because Rodwell offers more than just sitting like Gibson does (so far).
When Rodwell comes back, I'd much prefer Fellaini, Pienaar, Rodwell midifeld with Pienaar in the middle of the two. Cahill doesnt offer much, and Rodwell hasnt been let of the leash further forward.
It wont happen. But overall, I wouldnt say Gibson is doing anything special to boost Fellaini. I'd say its more the support on the wings giving the midfield more balance than just the 1 player. Bringing Rodwell in would boost the midfield even more.