I get this question a lot, “the windup vs the stretch, what is better?” The problem is the windup is almost sacred to the game of baseball but it really has no purpose besides a kind of confidence builder on the mental state of the pitcher. The windup represents the old style of pitching from back in the day when the pitchers would use the windup to get their arms moving faster like in the video clip here of Dizzy Dean. Now that we have learned that doing this is destructive to pitching velocity, the windup has become just an extra step to throwing in the stretch.
This is the next question I usually get about the two deliveries. I will refer to the science on this one because that is the only way to answer this questions. Here is the results and conclusion from a case study called, “Biomechanical comparison of the fastball from wind-up and the fastball from stretch in professional baseball pitchers.” It was performed at the American Sports Medicine Institute in Birmingham, AL.
RESULTS: There was no significant difference between the 2 pitch variations for the kinetic, kinematic, or temporal variables. The difference between the ball velocities was statistically significant, but the mean difference was only 0.2 m/s.
CONCLUSIONS: The pitching biomechanics between the wind-up and stretch fastball showed no statistical differences in joint kinetics, kinematics, or timing, and clinically insignificant differences in ball velocity.
CLINICAL RELEVANCE: The current results suggest that pitching the fastball from the stretch is not necessarily more stressful to the shoulder and elbow.
Read the case study here: http://www.ncbi.nlm.nih.gov/pubmed/17986632
I believe that the deciding factor of a pitcher who would either like to use the stretch or the windup without runners on base is the foot position issue. You can get your foot in a more comfortable and athletic position when in the stretch. This would really benefit pitchers who are playing on bad fields. You know that mound that has a crater in front of the rubber that annoys the hell out of you? Here is a velocity quick tip that covers how to effectively position your foot on the rubber.
Pitchers that prefer the windup over the stretch, when acceptable, usually say the reason is because they feel more comfortable in the windup. If this is the case for you or your pitchers then this is fine. The only problem is if there is a significant difference between the pitchers delivery when in the windup as opposed to the stretch. There should be no difference once the lift leg hip begins towards the target. Notice the video of John Smoltz below. His two deliveries are seamless between his windup and stretch.
I recommend pitching in the stretch more often because you will throw your most important pitches there. If you are more comfortable in the windup then this is usually because you throw more practice pitches in the windup. If this is the case, then I recommend throwing your bullpens in the stretch the majority of the time. This will also help you when you have runners on base. When runners are on base you must do your best to help your catcher to hold the runners on by being as quick as possible during your delivery. This means you may need to slide step. The problem is if you are a pitcher who likes to throw in the windup with a big leg lift, when in the stretch and slide stepping, you lose velocity. The key to not losing velocity in the slide step is focusing on the “Load” position. This position is when your hips are driving towards the target and you are squatting hard on your back leg while your hips are moving forward. If you work hard to build momentum in the “Load” position, you can build as much momentum as you do with a high leg lift. Read my article on “Lift for Show, Load for Doe” to understand more about the “Load.”
I also recommend, when in the stretch, to start with your head and hips just inside your drive foot. Have your feet past shoulder width and your lift leg hip ready to fire to the target. This will help you get your lower half moving even faster to the target which will allow you to build maximum momentum along with optimal speed to hold base runners on.
It is important to remember that whatever you do to your delivery in the windup or stretch they must match each other once the hips begin moving towards the plate. If this does not occur then it will be very hard to stay consistent mechanically through the entire game. This will have a big effect on your balls to strikes ratio.