For many years, the service could have been considered as Martina's biggest weakness, mainly due to a suboptimal form of the pronation with the elbow staying rather too low and the racket traveling rather too much on the horizontal plane after the impact. Over the course of the years, Martina was able to improve it a bit and her pronation did look much better later in her career. With the elbow.....
One of the bases of Jelena's success is her powerful forehand, which was clicked as having higher average speed than the forehands of the men's #1 seed Andy Murray (GBR) during the 2017 French Open. Jelena's forehand has an excellent foundation with a form of the takeback/backswing, which is bringing the racket into the appropriate hitting position very early. She doesn't have any potentially disturbing....
..Marat's service belonged to the most dangerous ones on the tour. His body size of 193 cm (6'4'') was surely very helpful, but also his service technique was very solid and Marat was well fulfilling the Service 3.0 requirements. As unstable as Marat was in general, his 1st service percentage through his career was just 55%, but of those 1st services in, he has had a 75% winning percentage and also his ace probability of 67% was quite high...
..back then, I was quite impressed by Jack's forehand, which he was unlike most other young Americans of his generation (Harrison, Young, Kudla, etc.) dominating rather by the body than by the arm action. He seemed to me like one who was able to stay immune to the widespread "infection" of the technique focusing at highest possible racket head speed and largely ignoring the importance of the body energy for the successful combination of power and stability/control in the strokes. It was, besides others, also Jack who brought me to the development of the model for the ideal body energy dominated modern forehand - Forehand 3.0...
Gael belongs to the best servers on the pro tour and his service mostly perfectly fulfills the highest Service 3.0 criteria of body energy dominance of the stroke. A typical sign of this is Gael's excellent targeted pronation in the "follow through 1". He appears to have discovered the essential aspects of the TENNIS 3.0 CODE for the service.
While Serena's service is being considered as the best in the game, service of her sister Venus is not much behind..., besides the technique also her tall body of 185 cm (6'1'') helps. The situation that Venus tends (mainly under stress) to tilt her head to the left side before the impact might be one of the reasons for her rather higher double fault rate than the one of Serena...
The above numbers tell us that Andy's service margins are mostly (besides aces) quite below the ones of his closest competitors. It's mainly his excellent return and rally game that make him to such a successful player he is. From the technical point of view, as I personally see it, a limited pronation and a rather unclear distinction between the follow through 1 and follow through 2 are the reasons behind Andy's lower service margins. Interestingly enough, Ivan Lendl (1st serve 56%, overall service points won 66%) had similar issues in his career.
Already in the late 90's, Mirjana belonged to the most dominant serving female players on the WTA Tour as she was one of the first of them who really understood the efficient use of the pronation. On the photos from 1998 shown below is well visible how fast she was able to pronate with the integration of the body energy already in the age of 16 years
Angelique's service seems rather a bit unnatural as she was born right-handed and was switched to a left-handed player in her youth. In tennis in general and even more so in women's tennis, playing left-handed must be seen as quite a significant advantage and this is the reason why some parents and coaches with big goals switch their natural born right-handers to the left-handers at a young age, quite a typical example here is also Rafael Nadal (ESP)
As a tall player of 198 cm (6'6''), Delpo has quite some power potential, which he is using in all of his strokes. His body parameters and solid technique make also his service to a dangerous weapon, despite partly missing one distinct element common to the very best servers of the history. His career service statistics (until the end of 2016) are quite impressive - in the total of 5563 service games - 3272 aces (against 1100 double faults), 64% of the 1st services in and 74% winning percentage on the 1st service points.
