Before I get into this, I want to address one thing from the first post:
That is irrelevant. We are not comparing the eras relative to each other, as in 'the players from such-and-such era would beat the players from an earlier era', we are comparing players within each era, as in 'so-and-so would beat his contemporaries'. Doing the former would be impossible, because tennis is always changing. Techniques in training, new equipment, changes in playing surfaces, the additional money leading to more players being trained for the sport, etc. make it totally impossible, and criminally unfair, to compare the eras to each other. It is also irrelevant because Federer and his contemporaries were trained in the same era and had the same advantages and disadvantages. It's therefore not more impressive that Federer beat his contemporaries because they were somehow better than earlier tennis players, since Federer also benefitted from those improvements in the training process.
Anyway, here's how I see it.
Tennis Channel's top 100 players features 3 of Federer's contemporaries (within approximately 3 years of Federer's age either way). They are Hewitt at #61, Safin at #80, and Roddick at #94. Federer is obviously at the top of the list.
Lendl was the #1 player through the latter half of the 1980s and Sampras was the dominant player in the 90s.
Lendl's contemporaries: McEnroe at #13, Yannick Noah at #85. Looking at Lendl, he started dominating at a relatively late age, 25, and a new generation came along, including Pat Cash, Mats Wilander, Boris Becker, Stefan Edberg et al. All of whom appear on the top 100, and all of whom won majors while Lendl was the #1 player. With the advent of the younger players combined with McEnroe, Lendl faced very tough competition.
Sampras's contemporaries: Agassi at #12, Courier at #42, Rafter at #70, Kafelnikov at #82, Muster at #95, and Chang at #100. Not to mention players who won majors while Sampras was at his best, including Sergi Bruguera with 2 RG titles, and Richard Krajicek with one Wimbledon. Sampras also crossed over, as a youth, with the end of the Lendl era and had to face some of the players listed above while they were in their primes. He crossed over, as an aging vet, to Kuerten and Carlos Moya, who were 5 years younger, and Hewitt.
Federer's contemporaries include Fererro, Malisse, Coria, Gonzalez, Davydenko, Nalbandian, et al. Underwhelming. Federer crossed over to Agassi as a youngster, and obviously to much better players in Djokovic, Nadal, Murray, Tsonga et al, as an aging vet.
Federer's most dominant years were 2004-07. His ages were between 22-26. I have spent time researching what an athlete's physical, athletic prime years are. The prime occurs between ages 16-26. Prior to 16, the body is too frail, after 26, there is a loss of youthful quickness and endurance that leads to less explosion and power and more stretches of middling play. This is true in any sport. The mental side of the game is something different. Every player is somewhat different. Lendl was a late bloomer. Borg was an early bloomer. Lendl maintained the mental dominance well past the point where his body was cooperating. Borg lost the mental edge long before his body broke down. Sampras lost the mental edge many years before Agassi. Injuries can play into this, as with Hewitt and many others.
All of this in mind, it appears Federer's best years were played in the absence of any great competition, and that somewhat accounts for his winning of 3 majors per year in those years. He did not have a contemporary rival that was near him in greatness, unlike Lendl/McEnroe and Sampras/Agassi. His career arc resembles Connors, who was not as dominant in his prime, but had the longevity. Connors, however, had a contemporary who is an all-time great, in Vilas. Federer lost a slam to a contemporary only once between 2004-07 (prime years), the 2005 Australian Open Semi, to Safin. Connors and Federer both have great rivals who are of a younger generation (McEnroe/Borg - Djokovic/Nadal). Both men stayed mentally and physically competitive past their athletic primes. Both resisted serious injuries (which probably accounts for the longevity).
There is one other thing to consider. Federer plays an attacking style of tennis that works much better on surfaces past generations got to play on. In his era, Federer has had to play on slow hard courts and a slowed-down Wimbledon. So, compared to many of the former players discussed, Federer can be considered somewhat hobbled during his career. But, this issue also would afflict Federer's contemporaries, many of whom were attacking players too.
All of this presupposes some sort of objective truth in TC's list, which is obviously not the case. But other than win/loss records, there is no way of measuring an era.
The plain fact of the matter is this: with the exception of the 2005 Australian Open, Federer's contemporaries failed to make any dent in his career accomplishments. That means those players were not in the same league as Federer. And that is not true of Connors (Vilas), McEnroe (Borg/Lendl), Lendl (McEnroe), Sampras (Agassi et al.) or Nadal (Djokovic). That is beyond dispute. So unless the era vs. era issue is what's being argued, which I already explained is impossible, I don't see the argument. Federer faced inferior rivals. That's the end of it.
But is Federer still the GOAT? I don't care. It's a non-issue. I enjoy watching him play and will regret his retirement when it happens.
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