FOR ENTERTAINMENT PURPOSES ONLY. Please believe any of the following at your own risk.
I refrained from posting in this thread for a while, but I'm finally giving in.
Here's the bad news: The sport has been dirty for a long time. It's only the sophistication and efficacy of the substances and methods by which players get an advantage that have changed. It's no longer even correct to call these advantages or even unfair because it seems the demands of the sport (i.e us viewers and our appetite for it) require players to do something about recovery, endurance and protecting their bodies and it's not isolated to a few either.
It's simply not possible for human beings, no matter how well trained, to perform day in and day out at the level we are witnessing today, without serious wear and tear on their bodies. The viewing public is naive to think that a good night's rest and whatever dietary fad (most commonly used red herring) is all that's keeping them fit and fiddle.
There are documentaries you can watch on how even back in the 70s, NFL players were on pain meds and powerful anti-inflammatories to be able to make it to the next week's game. Over time, these things don't stay in one sport. The human body is the same no matter what sport you play, and techniques cross-pollinate across sports rapidly.
As for the top guys, at this point, it's safe to say they're all using or have used some form of dope over and above the simpler stuff I described above.
Nadal was a human project, literally engineered to be the kind of player his Uncle and family had in their vision. He started getting HGH in his early teens and by the time he was eighteen he was already nowhere like what a normal kid his age would look. Gasquet and Nadal are about the same age and played juniors together. You can look at their childhood pics and see how scrawny Nadal was. To attribute his physique to training and genes is utter B.S. The fact that his other uncle was a pro soccer player should tell us they knew about methods to pump this kid up and they had the means and access to do so.
If you think that's so out of the realm, just read about Messi. Barca brought Messi over from Argentina at a young age to Spain so he could receive 'treatment' for weak legs. And what was the treatment? HGH shots to he would grow strong. They knew he had the talent at a young age, now they would make him the athlete they wanted and Spain has been doing this with great success across sports. Nadal has had exactly the same kind of 'upbringing'. If anything, they overdid it some respects with him and the musculature put a lot of stress on the body parts that don't just grow as much - ligaments and tendons - and those have been the source of his injuries. If the falling hair and tendonitis injuries don't convince you, that's fine. You can choose to believe what you like.
Federer it would seem did not much out of the ordinary for a while (i.e other than the routine stuff many others do - anti-inflammatories, pain killers and such), but you can see a transition at one point where he went from being chubby in the face to lean and gaunt almost. This isn't some new 'diet' or better training. The guy was already a top athlete having won multiple majors by that point; he didn't discover some new dietary magic pill one day suddenly. The theory is that TUEs were used for cortisone etc to have him lose fat while retaining/gaining more strength and apparently this has been done in cycling with great success.
I believe that Federer probably did not want to go down the HGH route or delayed the inevitable as much as he could given his competition. But he's definitely joined the ranks as far as the more sophisticated methods are concerned. EPOs may also be a factor, and Dubai as a 'training base' is definitely shady as hell because again, in that region you can get what you want if you have the money.
Djokovic is a clear cut case of doping as any. This guy went from a retiring, injury prone, inconsistent player to a behemoth like overnight. All because he dropped gluten from his diet. Yeah, right. All those shady characters in his posse, chinese medicine or whatnot - well that's EPO fixers for you. I've even read of some fixing rumors about him in his pre No.1 days when he still owed money to people who helped finance his journey. Russians I think.
Murray went the more traditional HGH route like a bunch of Americans, to gain lots of muscle. He went down to 'train' in Miami and lo and behold, lean chicken and broccoli turned him into a hulk. There is a reason all these athletes flock to Miami. It's a den of easy access to all sorts of pharma gear and doctors, fixers, and proximity to Latin American/Carribbean medical facilities that don't have any qualms about hooking you up with whatever you need.
Remember Odesnik? He was just a fall guy. Took one for the team trying to get HGH into Australia in quantities that couldn't have been for his personal use. He was their mule. Stupid yes, but folks denounced him and denied any association with him vehemently and became more careful.
So that's my take on the Top guys. I can tell you these aren't the only ones and they're not new. There have been hangers on and all sorts of characters around the sport for a while now whose job is to help these players out in that department. Remember Gil Reyes, Agassi's physical trainer? What do you think he did for Agassi? Spot him while benching? Remember Mardy Fish suffering from arrhythmia and quitting the sport... these guys Fish, Roddick and Gimelstob were all partners in crime doing the same stuff and somebody messed up with Mardy's cycle because he went for too much. Lost a bunch of weight (claiming to be from a low carb diet and a company selling slow-release carbs) and his results were improving when suddenly the side effects kicked in.
The Williams sisters have been doing steroids so long, they've turned it into an art. Again South Florida - golfers, tennis players, NFL & Basketball players they all flock there for the same reason. Like California doesn't have sunny climes and rich enclaves anywhere.