Sampras would be too powerful
Eddie, let me start this faceoff between Pete Sampras and Roger Federer with a surprise question: What was the major difference in the French Open final between those two paragons of clay-court tennis, Rafael Nadal and David Ferrer?
The answer: power, particularly the power of Nadal's inside-out forehand.
As that match demonstrated, power is the ultimate weapon, whether it's applied by a baseline-hugging, counterpunching clay-courter or a practitioner of the vanishing art of serve-and-volley tennis. And power is the quality that would give Pete an edge over Roger in a meeting of the two men at their respective peaks, on any surface but red clay (even I can't argue with the disparity in the records of our two heroes on that surface).
This being the 10th anniversary of Federer's first triumph at Wimbledon, we'll set our matchup on grass. I'm fully aware that the two icons met only once in their overlapping careers, and it was on the fast grass of Wimbledon in 2001. Federer won that clash 7-5 in the fifth. However, Sampras was already running out of steam at that point in his career (down to a ranking of No. 6 and wouldn't win a tournament that year) while Federer was just developing into a Grand Slam champ.
Pete had the most easy, fluid power of any player after the legendary Pancho Gonzalez, and nobody had a higher-quality serve -- not if you rate both first and second serves. That helps explain how Sampras played so many close sets yet won so many matches. He would just cruise along, holding serve, confident that he would get a look or two at an opponent's service game once any given set approached critical mass. When Pete needed a great return or two to go along with a momentary glitch or error by an opponent, he always seemed to find one. That, in the long run, is a talent worth more than any number of dazzling strokes or even the wonderful versatility of Roger's game.
It's silly to speak of "shortcomings" in either man's game; they rank Nos. 1 and 2 on the list of all-time Grand Slam singles champions. But I can't get beyond the fact that Pete seemed to be a fighter from a marginally higher weight division. And that would have been the decisive factor. The power he brought to bear was superior to that of his rivals, and at his peak, it would have been enough to impose Pete's game on Roger as well.
Federer would be too versatile
It's funny that you bring Rafael Nadal into this conversation, Pete. It was he who twice stood on Centre Court and watched as Roger Federer -- thanks to his "wonderful versatility," as you correctly put it -- added another Wimbledon trophy to his collection.
In those victories, Federer's long-undervalued defense, which seamlessly transitioned to match-altering offense, was a huge part of his success. Against Andy Roddick, who watched the same outcome three times, it was Federer's serve and return that were integral. He didn't let the American's biggest weapon overpower him and fought fire with fire, particularly when Federer swatted 50 aces in their epic 2009 title fight.
Roddick is not Sampras, not even close. Pete's power was unrivaled, but not unbeatable, even at Wimbledon. We saw that in 1996 and five years later against Federer. But even though Sampras wasn't in his prime -- to which I must add, neither was Federer -- Pete was still the defending champion and the grass surface was still slick. Federer played aggressive, attacking tennis and didn't let his idol's blink-and-you-missed-them service holds faze him. In this difficult debate between seven-time Wimbledon champs, it's a more significant result than people give credit for, and it's hardly unrealistic to envision a wiser Federer giving Sampras -- even circa mid-1990s -- even more trouble at the All England Club.
All three of these opponents illustrate Federer's greatest quality as a player: The man rises to the demands of the situation. That's particularly true at Wimbledon, where in 2003 Federer combated the pressure of winning his first major title and nine years later did the same when people were wondering if his Slam-winning days were behind him. It's too bad that someone already used the title "A Champion's Mind" when Federer's autobiography is written someday.
An in-form Sampras would demand the most of Federer, who has been beaten by big hitters at Wimbledon before. But an in-form Federer is a player without any weakness on grass and is widely considered the greatest player of all time. His slice backhand, to name just one weapon in his vast arsenal, would prove immense both on the ground and while returning. And I can't neglect to mention his searing forehand, balletic movement and pinpoint accuracy. Give me Federer's white blazer and all-around game over Sampras' lunch pail and cannon serve in a close one.