I don't know a huge amount about stuff like this. Was this just a natural evolution as the players got used to the new rackets that were introduced during the late 80s or were the courts all slowed down? You see Federer do a lot of S&V against Sampras. Did this change from S&V to the baseline play mean a lot of young players who were originally hyped up suddenly went crap? Or was it usually the case that anyone who was originally good at S&V was probably talented enough to hit from the baseline?