Only if De Gea signs a new contract could we say he played it well. But all he did was not go to Madrid and offer De Gea in that case given the reported events of the last 24 hours.
It remains to be seen a) whether De Gea can motivate himself (sure he will though), b) whether Van Gaal plays him at all if he doesn't sign a new contract - he seems to hold grudges after all and c) whether De Gea actually has had it with Madrid.
My guess is that Mendes is trying to cover is arse by now using spin to reduce collateral damage and retain his client.
If De Gea doesn't sign a new contract, and frankly, unless he really has had it with Madrid, then I doubt he will, then having De Gea for one year and then losing him for nothing is hardly a blinder.
Given that De Gea has harped on about family and home so much, somehow I doubt he is signing a new contract.