You make good points. Disagree about De Gea being past it and 4 quality players would propel them forward. However there has to be a plan or an idea behind the whole thing.
They need to instill that winning mentality again. Yeah you're right it's gonna take time.
I agree that De Gea has the potential to not been past it. But by signing that extention with a club that will not offer him the chance of CL in some years shows that he accept the comfort of the big money over the hunger for the big titles. And a player in the comfortzone is probably past his 100% best.