Thinking about this - flat shots vs spin shots.
For a flat shot, if it is hit on the frame, you are hitting a fast moving ball (horizontally) with a moment arm (distance from centerline of the racket) of maybe 5 inches. That is a lot of torque which must be resisted. A wider radius grip with more surface area being held will help resist the torque and put less stress on the elbow.
For a topspin shot, the racket is moving across the path of the ball. If a ball is hit on the frame moving perfectly vertically (on the side of the rackethead) there is zero torque on the racket. Though it is unlikely to happen exactly like this - though I have done this on several occasions - it is the limiting case. With a more vertical swingpath versus a more horizontal swingpath, the relative forward velocity of the racket and ball will be much lower and the moment arm of the impact point will be much less. There should be much less torque to resist in most cases of a mishit, and so less stress on the elbow and the rest of the arm.
Therefore, for a spin player, there should be less stress on the elbow on mishits and less reason for a larger grip size.
Also, volleys are hit basically with a flat racket face coming almost straight at the ball (unless you are hitting a drop volley with a ton of backspin). Volleyers should get more control on off-center hits with a larger grip.
Last edited by NLBwell; 12-13-2012 at 09:07 PM.