1.Indeed, Del Potro isn't the best model you can find.
2.Some think about patting the dog, but I don't really care the wording. I am talking about what happens with their forearm as they are about to swing, at the very end of their take back.
3.I know, it's a weird swing. That's why the researcher had put him in a third kind alongside of Agassi. I didn't pay attention to exactly what he was doing; I just know he's not in the optimally efficient kind given the data he piled and that's enough.
4.The tweaks I am talking about involve simple body position at given moment of the stroke. You take an average stroke and you improve it by adding in a few details -- pronation at the end of the take is one; ulnar deviation, wrist flexion and a supine hand position nearby contact that is reversed to a prone position and radial deviation after contact is a second one (that's what people call the wrist snap). Both aren't very hard to implement... most of the time, you need to add them into the movement; the high performance coach who wrote about it and studied it says most of his students don't need to get rid of details that should be out of the swing unlike what most people might think. He says they needed things to be added. The two above details are things to be added.
5.As for your Tsonga, here he is:
He does it too. It's more his elbow and forearm you should look at than his racket as his body position, the ball will make contact with and his intention might change how far the racket faces the ground. If the elbow tries to show its face, there's pronation, even if only mild.
6.I don't think we should use any movement besides our own, but you are being consequent with the above: I said we need to add stuff to make good forehands turn into great forehands... you do need to work on big movements before working on smaller ones and it's indeed a fast and easy change if you know how to teach it right.
7. The same coach resumed what details the best forehands get right that amateurs can learn without being exceptionally gifted themselves.
Originally Posted by SpeedMaster(Blog.Tennisspeed.com)
1) You need to pronate the elbow of your hitting arm before starting the forward swing – to the same extent as the players pictured earlier—to compensate for the natural supination – or opening of the hand causing the palm to face skyward – of the racquet elbow /hand to ensure that you can deliver the racquet face in a closed position – i.e. racquet tilted forward—at impact.
2) You can start to experiment with how steep or how shallow your upward swing path affects the resulting shot. The simplest way to do this is to start experimenting with how far below the impact point you start your forward swing. You might also experiment with the height at which your racquet hand finishes after impact. You may find that you produce more topspin when you shallow out your overall swing path and use a finish lower versus swinging more steeply upwards and finishing high – when the racquet hand finishes up at head-height or higher. And, you should note that this concept effectively runs counter to the “how topspin is produced” paradigm ingrained into the “stroke knowledge” of most tennis players and coaches possess.
3) You need to learn when and how to pronate your hand – or “re-pronate” is the more appropriate description—as you accelerate your racquet through the impact zone. Elbow Pronation in the impact zone is how you can support, stabilize and maintain the forward tilt of the racquet face at impact, especially when impact is made off-center. Elbow Pronation of the racquet arm at FFM and just prior to impact creates maximum racquet speed and acceleration to maximize energy transfer to the ball. In other words, Elbow Pronation plays a crucial role in maximizing both spin production and ball speed.
8. When I explained that it's easier to achieve consistent contact, I meant that your racket will behave this way and open as you swing. If you don't get into this position, you make your life harder for no reason.
In his experience, players who have implemented these advices -- and we're talking about ranked juniors, competitive players -- have seen their top spin production increase by as much as 40% on average and some of the flat hitters have nearly doubled it.