Transfer windows don't guarantee safety, progression, or even improvement. Crystal Palace have suffered the consequences of plenty of ineffective January windows where squad depth was added but not of sufficient quality in the past. Names like Kevin Doyle and Emmanuel Adebayor spring to mind, two strikers recruited in successive seasons who had such little impact they might as well not have been signed.
It was therefore imperative that, given Palace's critical position (18th) in the league, players would have to be signed that wouldn't just improve the quality of the squad but improve Palace's chances of surviving the drop.