^ Do not know the reason for the rule change. Prior to 1903 players were allowed to walk or run to the service line to deliver the serve. I believe that late in 1959, the rule about keeping one foot on the ground at all times during the serve was amended.
I did not change from that old style until the early 90s (when I started studying Sampras' serve). I still see many players on the court these days with that older style.
Roger Federer serve motion
Pancho Gonzales serve motion
Stanimal serve motion
Originally Posted by taurussable
... racquet drop (no time racquet hitting face is pointing up, Sampras and Federer's racquet hitting face has time of pointing slightly up during racquet drop)
I found there are two kinds of racquet drops, Sampras, Federer is one kind
Pancho and Wawrinka is another kind, their racquet drop forms a plane which is perpendicular to their body.
I am still looking for serves similar to Pancho.
It appears the the orientation
of the racket face at the trophy
position is different for Roger than for Pancho. Stan W might be supinating his forearm early in the racket racket drop from his trophy position.