Actually, what makes Federer's forehand so good is not any of these traits in my opinion. It's his DISGUISE. As Hewitt said, you don't really know where he's going with it. Federer stalks the ball, and has a very stealth swing. It's almost like he's sweeping the ball in with a magic cape, then shoots it out at random. It's like playing a ball machine with random oscillation, but where the actual machine doesn't rotate one way or another to give away the direction...then, that's REALLY tough no matter the pace. However, if the machine rotates, then it's far easier given the same pace.
Federer's forehand is not the hardest in the game, nor does it have the most spin, nor does he get the most angle, nor does he hit the ball the flattest and most penetrating, etc. What he does have is a remarkably adaptable and fluid forehand that allows him to feel comfortable from deep behind the court defending (where Agassi's stroke is too rigid) with top like the claycourters, allows him to take the ball on the rise like Agassi in a half-volley manner, allows him to hit angled shots with the same prep as he does his drive forehand, etc.
Sampras and Korda hit purely flatter, more penetrating forehands, but were inconsistent. Bruguera hit it with more viscious topspin, but would often tire periodically through matches because of the energy expenditure. Berasategui could slap shot, string ray winners at any time from anywhere on the court; but his backhand was so bad it didn't always matter, haha. Courier hit a consistently heavier forehand, but with no capacity for angles or variety. Gonzales, well no one hits it harder than him; but at the same time like Bruguera the energy expenditure often leaves him periodically petered out and out of gas during matches (see what happened to Roddick when he started flailing at Wimbledon this year...effective in spurts, but what happens when your turbo boost take goes empty?). Roddick's got more power and spin AND racket head speed (yes, Federer generates a lot of it, but there is no doubt guys in my mind that guys like Roddick, Bruguera, Ferrero, and Gonzales generate more...but at the same time they have to waste so much more energy doing so). Santoro can carve up any angle on the court at any time, but problem is that's all he got...somebody left the mustard off the hot dog. Agassi's got an extremely precise forehand with pace that he can take on the rise with his short swing, punchy swing...but this compact swing also makes him rigid and inflexible when defending, on the run, or pushed behind the baseline.
All in all, what Federer has going for him is what Rios did when his forehand was at his best...a fluid yet compact swing that allows him to disguise his shots better than anyone else, hence leaving the flat and wrong footed more often than normal. I.e. You ask any pro to hit an extreme angle and they can do it, noww make 'em do it so that it looks exactly the same as their power down the line forehand...THAT is where Rios and Federer have/had the competition beat at their best.
If you break down their forehands, they were never really THE best in anyone category, but it was their silky preparation that almost LULLED you into sleep.
What Rios and Federer also have are forehands that are neither extremely western nor extremely eastern, nor is their preparation more suited to one or the other. Everything just kind of falls into a happy medium. As such, it is their balance and adaptability on the forehand under ALL conditions that allows him them to MINGLE but not necessarily standout under ANY situation until they get that juicy sitter to go for the knock-out blow...which really any competent pro should be able to deliver, should they be able to hang in a point long enough to get such a juicy ball.
Knowing all this, this is why when at their best Federer and Rios never seemed to be pressured on their forehand. It was simply the symmetry and balance of it all, being able to deal with any situation like water, absorb any blow like water...and, of course, like Bruce Li they too could strike fast when you least expected it, even knock you out with a one-inch punch, haha.
Bottom-line, Federer's forehand is not the best because he hits the hardest, with the most spin, or with the most angle; it's because you can't read which shot he's going to employ. It's like with the serve, Roddick can place the ball well and hit every kind of spin in a most VICIOUS way and with unmatched speed...but several opponents have commented that his serve is very readable. Leaning in the right direction on the return of serve is half the battle...
Why should it be any different on the groundstrokes? When I watch Federer's forehand, I'm never just outright blown away by his pace, spin, angles, or ability to take the ball on the rise. As I've said, I've seen all of this done just a hair better by the "specialists" in each one category; but I've never seen all these elements combined with such across the board mastery. If the best score were a 10, Federer would be an 8.5 across the board. When you factor in that you can't read his shot, then that effectively makes those individual 8.5 score 9.5s across the board. Factor in 9.5s across the board, and you're going to have opponents who look like they don't know what hit them...and more importantly, from WHERE. Collectively, Federer's forehand is like Voltron, a lot of really nifty lion robots with nifty individual traits that alone were not necessarily FORMIDABLE but certainly *skilled*. COMBINED, however, they form Voltron, a truly unstoppable force with a really, really cool sword to boot, haha.
