Join Date: Dec 2012
Just my opinion. I had mono about 5 or 6 years ago and I have never felt quite the same physically. It's quite a debilitating illness that can have a very long term effect on the body and never really leaves. It's not just me, many people have had this experience as well (see Robin Soderling).
Getting mono in the beginning of 2008 explains Federer's sudden drop in form IMO and why he has never been able to reach the heights he did from 2004-2007. He has never quite gotten over the illness, but being the great player he is the man is still a slam threat. Why else would he, at the mere age of 26, have such a noticeable drop in form compared to the previous years. I know I'll probably get some flaming for this but IMO this is the most likely explanation and its amazing that Roger is doing as well as he is these days.
Compare Federer to Djokovic, Murray, and Nadal who are all about the same age(26) that Federer was in 2008. They have games that are much more physically demanding and yet people scoff at the idea of them declining. It doesn't make sense to me that Roger would just drop off like that without an explanation.
That said, there's a mild decline in 2007 and a steep decline in 2008 that he never really recovers from again (i.e. returning to the 2007 level). The potential is obviously still there - see Australian Open 2010, WTF 2010 and 2011 and Wimbledon final 2012 for examples), but the overall level is not the same.
Imo, Federer's mono helped Nadal's cause in 2008 just as Nadal's knees helped Federer in 2009. Had neither happened, it might have been another year, before the passing of the torch.
As to why we don't speak of the current players imminent decline, I think there's one very good reason for that. In 2008, Fed was as 'old' as fellow top ten members like Davy, Roddick, Ferrer, Nalby and Blake, but he had proven his superiority over them. However, a crop of youngsters were emerging, Nadal (already a veteran), Djokovic, Murray and later Delpo.
Now a days, there's not a single player younger than 22 in top-20 and not a single below 21 in top-50. So who's to replace Djoko, Murray, Nadal even if they do drop? (and remember, Murray and Djoko are not due for their 2008 year before 2014). As for Nadal, we've been talking about his possible decline for years and although there are no sure signs of it, it may happen this year as it did with Fed in 2008.
As for Djoko and Murray, they might be a whole lot hungrier than Fed was in 2008 come next year. Certainly, Murray should be. That's a factor too.
All in all, I do agree that the mono probably took the top of his late peak years (2008 til early 2010) and that 26,5 is early to start dropping that much (though not compared to say Borg, McEnroe, Becker etc.) How much did he drop and how much did it matter? Impossible to tell.