Problem is, it is consistent. A true 120 MPH might show up as 115 MPH. A slower serve then would show up with less of a difference as the percentage of error would not affect the slower serve as much. With regard to 1-4, 1) Andre Agassi, when he was into lifting weights, hit the ball with less pace. Weight lifting for strength does not help tennis. 2) Well, considering that most pros play with racquets which are clones of models 15-20 years old.....racquet technology hasn't helped. What has helped is matching characteristics and stringing. Please note that I said "most pros". I refer to Roger Federer, Andy Murray, and Djokovic as pros who use older frames and Nadal as one who does not. 3) You have no empirical data to prove that Bjorn Borg didn't hit as hard as Rafael Nadal. The instrument in Borg's hand didn't tranlsate the strike in the same manner as Nadal.... Did that hurt when you pulled that out of your arse? The ProStaff not good at serving? Did anyone mention this to Sampras? Edberg? Hell, even Connors served better with the ProStaff than he did with the T2000.