For the sake of clarifying this discussion, I believe we need to define athleticism verses talent, verses being a champion.
To be considered an all-time great champion in any sport, you must have a high degree of all of these factors:
1.)
Raw physical athletic ability: Speed, strength, explosive power, flexibility, endurance, overall fitness, etc.
2.)
Mental toughness: Ability to concentrate, ability to overcome frustration, ability to overcome nervousness, high pain threshold, etc.
3.)
Development of sport specific skills: Ability to hit all types of shots/perform all types of required actions at an elite skill level.
4.)
Sport specific talent: A combination of physical and mental characteristics that can make you naturally excel at one sport over another.
5.)
Competitive awareness/intelligence: Ability and awareness to understand and implement the correct strategy in specific circumstances.
6.)
Luck: Opportunity to play, access to good coaching, financial backing, lack of accidents/injury/illness, etc.
I believe that what the OP's coach was probably talking about was the first characteristic, raw physical athletic ability. In that sense, I would have to agree that Gael Monfils might be at the top of that list among current tour players.
I am not basing this on the color of Monfils' skin or peer pressure. Rather, my opinion of his athletic ability comes from two things:
1.)
First hand observation: I had front row seats behind the court to watch Gael Monfils' 1st round match at the US Open this year verses Michael Russell. In comparison with all of the players we watched this year, Monfils was the most impressive to me in terms of raw physical ability. Despite inefficient footwork, his speed was so amazing that he could cover all parts of the court like lightning, and we watched numerous leaping, scissor kicking, Sampras-style overheads that appeared to show off a 36+ inch vertical leaping ability. In terms of power, he could hit huge shots (booming forehands, 140+ mph serves) seemingly without effort. And for flexibility, all I had to see was the point where Russell hit a drop shot and Monfils sprinted in, slipped on the court, and still hit a forehand winner while doing the complete splits.
(I know they showed that particular point on television in the CBS US Open highlight show as we happened to look up at one of the big screens in Times Square later that night to see it... and video of my wife and I cheering after the shot! There's nothing quite like randomly looking up and seeing your face on a giant television screen in the middle of New York. By the way, I've been trying to find a copy of the that particular highlight, but have not found it yet on YouTube or elsewhere.)
Speaking of YouTube, here is a pretty impressive point by Monfils:
http://www.youtube.com/watch?v=SAlnGDMRcZI
2.)
French federation athletic testing results: While we were watching the Monfils match at the Open, we were listening in on the radio broadcast over the free headsets that AMEX was handing out. On the broadcast, Jim Courier mentioned that most sports in France are federation backed. For the past 50 years or so, apparently, the various French sports federations make all of the athetes they work with perform a standardized athletic test to determine their relative level of physical capability. This test is supposed to measure pure speed, power, flexibility, endurance... all the things we have mentioned in regards to raw athletic ability. Anyway, according to Courier, Gael Monfils tested out higher than any other athlete in the history of the test in France
in all sports! (This means his results were compared not only to fellow tennis players, but basketball, soccer, cyclists, etc.)
As others have mentioned, Monfils may have deficiencies in several of the overall areas that hinder him from being a great player right now, but his raw athletic ability seems to be his biggest strength. If he could improve his overall skillset, mental tougness, and competitive awareness/intelligence, he would be very, very tough to beat.