Unless you come from the Domingo Ayala school of Beisbol, who believes power pitching is with the arm:

“I have never seen a power pitcher with a flame on his leg!” – Domingo Ayala

Then you should have no problem understanding how important the legs are to not only pitching velocity but arm health.
Mat Latos is learning this lesson the hard way. The Mat Latos’ equation that lead to his recent forearm strain was; poor pitching mechanics + knee surgery = forearm strain.
The lower half is not just important to increasing pitching velocity but it is critical to protecting an arm like Mat Latos who is required to not only throw hard but throw a lot.
In this article, we will look at the flawed pitching mechanics of the 6-6, 244lb Mat Latos. I will also define why the lower half is so important to protecting the throwing arm and how the MLB is the worst at teaching lower half mechanics. 

Mat Latos Flawed Pitching Mechanics

Why do most big men like the 6-6, 244lb Mat Latos have lazy mechanics? The answer is because these big guys can get away with it but only for so long. They may still continue to throw hard but wear and tear is catching up to them faster than most.
Mat Latos has a very average drive leg compared to his size. The issue is, I am not sure if his pitching arm can handle his drive leg at max effort but it definitely needs to work harder than it currently does. His drive leg barely generates force based on his body size. This is why his stride is average to below average. He uses his front leg extension (2X) at max effort before pitch release to make up for this lack of leg drive.  This will produce high ball speed but isn’t as efficient as using both legs to drive the hips.
If you watch the 3X Video Analysis I did on Latos below you will see, even in his warmup pitches, his front leg goes into hyperextension which is overly aggressive. This is more than likely the link to his recent torn cartilage in his left knee which forced him to have surgery this February.
Just following his left knee surgery he was then put on the DL for a strained right forearm. Do you think the breakdown of the left knee had something to do with his arm injury? In my book of 3X Pitching it is an obvious link. What I have experienced when working with pitchers who have had landing leg surgery, usually due to the hyperextension of the front leg, is that they come back to pitching with a soft front leg. I believe the leg goes soft because it is now protecting itself from further damage. The effects of this soft front leg into pitch release is a small or large decline in pitching velocity first and then the issue of added horizontal adduction, that I talked about in my article on Kris Medlen’d 2nd TJ surgery, which leads to arm injury.

Importance of Pitching with the Legs

I truly believe that the poor leg drive or the inefficient leg drive between the back and front leg is the link to all arm surgeries. Overuse and poor physical fitness just exaggerates this issue. To help prove my point all you must do is look at the math from the study below. When the legs reduce the work load the arm is forced to overcompensate.

Kibler and Chandler calculated that a 20% decrease in kinetic energy delivered from the hip and trunk to the arm requires a 34% increase in the rotational velocity of the shoulder to impart the same amount of force to the hand (1).

If a 20% decrease in kinetic energy, which is the energy moving from the ground forces generated by the legs up the body, is increased to 40% then look how dramatic the difference in the outcome. The arm now has to generate 68% of the forces to make up for the 40% loss from the legs. Not only is this detrimental to pitching velocity but more dramatically it has severely increased wear and tear.
The problem is with the legs approach to pitching is that the majority of pitching coaches and instructors do not know how to coach the lower half. I have yet to find anyone coaching the linear force vector, torsion or the sequence of movements that allow the pitcher to use a leg drive to increase hip rotation movements.

MLB and the Weak Lower Half

Not only does this poor coaching of the lower half exist in amateur baseball but I have also continued to find evidence that it also lives in Major League Baseball. For example, in my article of the downfall of Bobby Parnell, the Met’s have him performing drills like the conventional “Balance Drill” which is an obvious poor understanding of the lower half mechanism.
Why would the MLB promote this poor understanding of pitching mechanics? Do they not read the studies? I believe it is because they believe slowing down a pitchers delivery will protect him. The problem is the science shows it will have the opposite effect (1). The reason is because when a pitching coach tries to slow down a pitcher it always starts with slowing down the stride. “Lift up, down and out.” “Come to a balance.” “Control the stride.” “Land soft on the toes.” This is common cues that coaches use to slow down the lower half which will reduce the stress on the arm only if the pitcher reduces his velocity at the same time. The problem is these pitchers can not afford to reduce their velocity, so they find themselves slowing down their strides but then trying to keep their velocity up. This is the perfect way to double or maybe triple the wear and tear on the throwing arm.
The best advice I can give to a pitcher who has coaches who are instructing them to slow down their lower half and at the same time they expect them to deal on the mound, is to please the coach in the moment but then go back to the more efficient and effective approach of a dynamic lower half. In the case of Mat Latos, he must learn that his front leg was overcompensating for his lack of leg drive and now that his front leg has broken down, his throwing arm is paying the price.

Pitching Reference:

1. Shane T. Seroyer, MD, Shane J. Nho, MD, Bernard R. Bach, MD, Charles A. Bush-Joseph, MD, Gregory P. Nicholson, MD, and Anthony A. Romeo, MD – The Kinetic Chain in Overhand Pitching – Its Potential Role for Performance Enhancement and Injury Prevention – Sports Health. Mar 2010; 2(2): 135–146.