Originally Posted by PureCarlosMoyaDrive
Well, using Grimjack's base knuckle (which I also believe is the main issue), then the full western is not impossible. in fact, I hit with that grip sometimes. You can really rip the ball with that grip, but can't go flat at all really. Therefore, with me occasionally using it and still being slight successful, then I can easily see a pro using that grip.
Should probably be noted that there are
players who rotate beyond this point, just as there are players who hit with continental grips. These are not as biomechanically sound for the purposes of driving the racquet through the ball, but offset that with other advantages. For some players, there is a need to hit a "western style" FH with what amounts to an upside-down continental grip, which moves that knuckle one more bevel beyond the traditional western. This is either due to unusual arm-wrist geometry necessitating this twist, or else simply because they learned that way young and became proficient with it. Likewise, although the driving force of the hand doesn't get behind the continental as well as with some other grips, it offsets that with amazing versatility.
But that's grips for you, I suppose.
To the original topic, yeah, lots of pros use western FH's, and lots more extreme SW's.
Link to grip comparison of Sampras, Agassi, and Muster (with closeups).
There you can see Muster's western pretty clearly, and specifically how far beyond Agassi's SW it goes.