Well folks I have had time to digest the article and had time to cool off, trying to not get my emotions involved in this thread. This is the type of stuff that can really irritate me, especially when it comes from "authorities" in tennis. However, film doesn't lie and I hope that the following information can allow us to put this to bed - for good.
So let me start saying that Eric couldnt be more correct if you paid him. Both Eric and I are teaching professionals (with Eric being in an active status). So for now, two teaching pros have learned that the "wrist snap" teaching and emphasis is a myth more than it is reality. I am sure Mahboob isn't far behind to post his comments supporting this as well.
There are also many other professionals "in the know", people who have studied pro film, not just looked at them, but studied them and have also determined that the wrist snap is a myth. Trying to do something that isn't there can be harmful to your health. The human eye can not pick up the subtle movements of the body during a fast motion and is only capable of picking up where something started and how it finished. From there it sort of fills in the blanks and that is were things can be misinterpreted.
It is no secret that a loose arm, shoulder region, and wrist (which means a loose grip) is essential in transferring energy to the ball. There is no if's, and's, or but's to this, it is pure fact.
So lets review what is it that generates the racquet head speed necessary to hit a hard fast serve and the role of the wrist. We are going to isloate the arm and the shoulder region and pretend that the lower body and the torso was initiated properly to help transfer the kenetic energy.
HOW DO WAVES BREAK ON THE SHORE?
Your probably wondering "what in the world does this have to do with the role of the wrist in a serve"? Well it has a lot to do with it so please bear with me.
Waves are generated by winds the whirl around the surface of the water. The stronger the wind the bigger the waves. Most of the waves we see that break on a beach are generated miles away from the shore. When a wave is generated and travels through deep water (keeping things simple) a swell will move towards land. A swell in the ocean is a wave but hasn't broken yet.
As the wave or swell travels closer and closer to shore, friction from the ocean's bottom causes the bottom half of the wave to slow down while the upper half without the same friction continues at the same speed. By the time it reaches shallow water, the difference in speed of the top half of the wave is so much greater than the bottom half that it "breaks" or folds over itself.
In California, the continental shelf (the bottom surface of the ocean) gets shallower slowly so that the bottom half of the wave slows down gradually. When it reaches a point where the bottom half cant keep up (shallow water), the wave breaks. But the wave breaks much slower than compared to a wave that breaks in Hawaii's North Shore. Plus, the winds that generated the wave in California's shore tend to be less severe as compared to the winds that generate waves on the North Shore of Hawaii.
On the North Shore of Hawaii, the waves do not slow down gradually as they do in California. There is no continental shelf to gradually slow down the bottom half of the wave. In Hawaii, the winds that generate the waves you see usually originate from Alaska which are very powerful winds. They also generate these waves in very deep water (some that are moving so deep you cant even see the swell on the surface) that travel 30 mph and sometimes faster.
When the wave reaches the North Shore, very little friction has been applied to these waves. On top of this, Hawaii's North Shore's shelf "suddenly" gets shallow and is not gradual like it is in California. The pressure slowing down the bottom half of the wave is tremendous. In other words, the wave or swell comes from deep water to shallow water very quickly.
Since the shelf in Hawaii acts like a sudden "braking" mechanism, the top of the wave is suddenly thrusted forward and upward which produces the very powerful waves you see on TV and what Hawaii's waves are famous for.
If you have read this, you will be able to pick up where I am going with this. You would see that the swell moving through the water resembles the coiling and the torso/lower body movement that will eventually transfer the energy to the shoulders, arm, and wrist. the braking mechanisms are a lot like what happens as one body element transfers the momentum to the other body element. The water represents the looseness of the body and the arm during the serving motion as it moves to meet the ball.
The bottom-lne to all of this is the sudden slowing down of one part while another continues is the "braking" and accelerating that needs to happen in the serve. Flexibility and looseness is what is important to transfer this moving energy, not a purposely done wrist snap as the force that initiated the motion has been completed (the legs, hips, and shoulders).
THE SERVE
When the shoulders slow down by using the non-dominant arm to "brake" or decelerate them, the arm continues to sling forward. Look at Roddick's serve closely. Notice the looseness in his shoulders and the extention he gets at his elbow. Notice the shoulders stop rotating once they are square and it flings the extending arm into the ball. Also, notice the wrist did not "snap".
As the arm slows down, the wrist is slung forward, when the wrist slows down (usually right at impact, the sudden force against the ball causes the wrist to slow down), the weight of the racquet is then forced downward (or breaks) as it has no other place to go - much like a breaking wave. When a wave is breaking the force is dissappating. The same with the serve. You want to make contact when the elbow has fully extended, this is when you are applying the maximum force generated by the legs, hips, and shoulders. The forward and upward energy at this point produces the "bang" you want in the serve then the wrist bends down from the transfer of force to the racquet.
So lets look at why the wrist needs to be loose and when it actually performs its role in the serve.
If you study professional serves you will realize the wrist is most involved when the arm stops or brakes as it reaches full extention. Look at the images for proof. When the upward swing starts in the serve motion, the wrist is thrusted back (lays back) and as the shoulders brakes, the arm begins to transfer the speed to the ball, the wrist isnt in a position yet to break (or catchup) yet and since it started out in a stopped position at the begining of the up swing, it is forced backwards or is laid back as it travels up with the arm. When the arm reached full extension, this "braking" cause the wrist to sling forward and the racquet hits the ball as illustrated below:
The non-dominant arm can be looked at as that shelf in Hawaii's waters. The arm/shoulder/hand is the water - fluidness. The top of the wave at its maximum peak is the the wrist. Look again:
If you learn nothing from my words above, learn this. It is the elbow extending that provides the "brakes" at full extension that allows the wrist and forearm to catchup and transfer the built up speed into the ball. Not purposely snapping the wrist! So, keep a loose arm AT THE ELBOW and extend making contact at full extension, the rest will take care of itself.
Take a closer look at other pictures for more insight:
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