I'm not ready to write his obituary, but since Wimbledon of last year he's been more equal to the Tsongas, Berdychs, and Del Potros of the world - that's what the record shows. Ferrer belongs with that group because of his incredible consistency and the amount of tournaments he plays; he's not capable of the same level of play as any of them, and talent-wise is more of a #8-12 type player. I think his ranking is largely due to the fact that his "performance floor" is still quite high.
I really hope that Federer pulls himself out of it, but we've seen a couple drops. He was playing at a very high level from around Paris in 2011 to Wimbledon in 2012 - an elite, #1 level. Then from the Olympics and US Open through about the WTF, he was a notch down but still easily in the Big Four. But for all of 2013 he's been a further step down and playing more similar in level to the second tier of players, the near-elites (Tsonga, Berdych, etc). So the trajectory is not good and shows continued decline since Wimbledon - that's not just a month or two but the better part of a year.
My hope is that we're seeing is just a down cycle, and that he'll play better through the summer and fall - and that this is just his aging pattern, ups and downs, and that he'll be able to be a contender for the next year or three. But again, the vast majority of players make a major dip at this point in their careers, and it is only the rare Tommy Haas and Andre Agassi types that have a resurgence. I think Federer is capable of this, but he needs to work through it and not get discouraged. But even so, I wouldn't be surprised to see him in the #5-10 range for the next year or two before retiring sometime in 2015 or 2016.