We all know AD doesn't have a job if he cannot wind his audience up.
On the face of it, it's a perfectly reasonable question, where WOULD we be this season without GB? Mid-table maybe, not fifth anyway .. But the same argument can be applied to GD. Without his goals we might also be mid-table. Without GB, GD and Lennon we'd likely be struggling near the drop zone. And without Friedel, Lloris, Walker, Vertonghen, Caulker, Sandro ...
You get my drift.
The point is we HAVE him. We risked £millions when he was a kid and persuaded him to come to WHL. Fergie was tempted but he held back. So now we are reaping the rewards for our investment. And if (or sadly, when) we sell him for £50m we'll replace him with someone else who can help us continue to compete at the same level.
Ergo the question is pointless.