The fact is you're looking at the "stat" that he cost of 15 points last season and using it to assume that we'll be 15points better off next season with a new goalkeeper. That's just dumb. However comparing him against other keepers, or even better, against a keeper we've been linked with, actually might give us some useful stats.
It's also worth remembering that despite him being shite, sometimes he's an outstanding shotstopper, and would have saved a lot of shots other less error prone keepers wouldn't have. You have to bear this in mind because you'll probably find your magical 15points slowly becomes closers to 5 all things considered.
It's not that I don't want to replace him, it's fast becoming essential that we do, I'm just fed up of all this hyperbole.
And yes I know we'd have done much better with De Gea in goal, but we'd also have done much better with Aguero up front.