St. Louis Cardinals: Breaking Down The Pitching Mechanics Of Alex Reyes

Sep 29, 2016; St. Louis, MO, USA; St. Louis Cardinals starting pitcher Alex Reyes (61) celebrates after getting the final out of the sixth inning against the Cincinnati Reds during the sixth inning at Busch Stadium. Mandatory Credit: Jeff Curry-USA TODAY Sports
Sep 29, 2016; St. Louis, MO, USA; St. Louis Cardinals starting pitcher Alex Reyes (61) celebrates after getting the final out of the sixth inning against the Cincinnati Reds during the sixth inning at Busch Stadium. Mandatory Credit: Jeff Curry-USA TODAY Sports /

St. Louis Cardinals top prospect Alex Reyes has a partial tear in his Ulnar Collateral Ligament (UCL) and will require Tommy John surgery.

The St. Louis Cardinals again must face the news of Tommy John surgery (referred to as TJ hereafter). It doesn’t take a complete tear for TJ surgery to be necessary.  This surgery can occur with several different injuries to the ligament in the elbow.  That said, TJ hasn’t been a death sentence to a career.  Many pitchers come back from it very successfully.

In an article released in March of 2015, the author questions the success rate of the surgery stating that there are plenty of pitchers, mostly relievers, whose careers fizzle after having TJ.  The article also states that they may need surgery again.  But that is not necessarily a fault of the surgeon.  Certain motions in the delivery of a pitch can put extra stress on the elbow, raising the possibility of UCL damage.

Some pitchers have more durable arms that can hold out without surgery.  Quite frankly, just as with anything in sports, it can come down to dumb luck.  Even pitcher with the worst mechanics may not get hurt, while beautiful mechanics can result in a UCL tear.  Such is baseball.

Alex Reyes has the mechanics that would warrant arm trouble.  And it has. So the first step in his recovery would be trying to find mechanics that are better for his arm without losing his effectiveness.

In a mechanical breakdown, it is important to break a delivery into isolated parts.  I will be looking at the delivery of Reyes through four steps of pitching mechanics: balance point, power slot, the turn, and the follow through.

Balance Point

Credit: Mark Harrell/Springfield Cardinals
Credit: Mark Harrell/Springfield Cardinals /

The balance point is often taken for granted.  While it may not be the most important part of the delivery, it can screw up everything if not done correctly.  This step in delivery is the point where the pitcher often has a leg kick, or slide step depending on the situation.  It’s purpose is to get the pitchers weight back on the drive leg, so it can then be used for maximum power towards the plate.

As far as creating problems in the arm, unless the pitcher leads with the shoulder instead of the lower half, then there won’t be an arm problem that can be blamed on a balance point.

The picture above shows a good balance point from Reyes.  His weight is back and his front shoulder is not diving towards the plate.  His hip is what is going to lead out, without it being pushed out, which is the ideal movement forward for a pitcher.

If a pitcher dives out with their top half, then there will be more stress on the arm because the legs are providing less power. Without the power being generated from the legs, it puts the load of the delivery on the arm.

Power Slot

St. Louis Cardinals
Jeff Curry-USA TODAY Sports /

The power slot covers the stride out and landing.  There are many parts of this position that can go wrong to put more stress on the elbow, and arm as a whole. But as the name suggests, a lot of power toward the plate is generated from this position.  The above picture shows several good things from a velocity-gaining standpoint.

First off is his legs, to an extent.  This specific picture shows the back leg as it pushes off of the mound to generate the forward momentum and power from the legs.

The second velocity-gaining positive is Reyes’ throwing arm.  His front arm shows he is still closed off, meaning he hasn’t started the turn towards the plate.  Meanwhile, his back arm is already generating torque by being cocked over towards first at the shoulder.

This picture is at the very beginning of the turn as well so it also shows another huge factor behind the velocity of Reyes: his hip separation.

The separating is somewhat complicated to explain but, put as simply as possible, means that the hips start to turn a split second before the upper body creating tension throughout the mid section.  This tension will work as a coil that will spring undone with the upper body turns, generating power.

There are a few parts of his positioning that are cause for concern.  Going from the legs up, it starts with the stride.  A good stride is considered to be 90-100 percent of the pitchers height.  Reyes is 6’3″ and takes a stride that resembles the 6’0″ Carlos Martinez.  While this may not play the biggest role, it certainly contributes to the problem.

Reyes has an average fastball velocity of 96.5 MPH from his time on the St. Louis Cardinals last year.  If he isn’t reaching his maximum stride potential, then he isn’t reaching his maximum stride power.  This means his arm takes on a bigger role in generating that upper-90s fastball.

The burden on the arm of Reyes can be seen as one of the other positions that can be cause for issue.  The angle of the picture above makes this difficult to see. I recommend watching a fluid video of his delivery for more investigation.

That being said, in the position shown in the picture above, Reyes has a bend in his elbow that puts the ball near his head.  This is the start of a potential chronic arm problem when coupled with the turn.

While the problems of stress on his arm start with the power slot, they are not isolated to this specific pitching position.  Pitching delivery is a complicated process that requires the whole body to work together for maximum power and overall safety of the arm.

The Turn

Jeff Curry-USA TODAY Sports
Jeff Curry-USA TODAY Sports /

This position is where everything culminates into the main elbow stress for every pitch.  The turn takes the mechanics through the actual release of the baseball.  A good turn will be the release of all the power built up through this point from the legs and arms.  This motion is the uncoiling mentioned earlier.

Reyes turns well in the lower body.  His hips fire through first creating the separation and tension for the rest of his body to create good torque towards the plate.

Even though I have been harping on his arm taking a lot of the workload of his fastball, the turn is helping handily in providing the power.  But based on his mechanics leading up this point, his arm is still doing a lot of work, creating potential problems, like his recent partial UCL tear.

The above picture really tells the whole story.  To start, he is off center in his delivery, you can tell his body is favoring the first base side of his body before the ball is even released.  While this would have no affect on his arm, it can affect his control.

The main focus is looking at his arm.  Reyes’ arm is almost at a 90-degree angle on the release, which is very good.  That external rotation can be seen on most, if not all pitchers during action shots of this part of a delivery.  The problem with his arm is that it is in a very similar spot to where it was in the power slot.

With the upper body rotating, the arm will move some but Reyes’ arm is dragging behind the body. This means when his arm whips through there is a lot of pressure on the elbow.  And Reyes has an arm that goes quickly.  One of the fastest I have ever seen.  Which, while good for his velocity and movement, is not good for the health of his arm while it drags the way his does.

Arm drag itself is not a detriment.  It isn’t good, but in a lot of cases it won’t be the sole reason for an arm injury.  In the case of Reyes, it is the starting position of his arm that causes a huge issue. The ball being by his head in the power slot moves right into the 90-degree external rotation without much actual movement of the arm.

Because of that rotation with such little movement, Reyes shows great shoulder flexibility, which can aid the explanation of his quick arm.  But in the end it puts too much stress on his elbow, which is a red flag moving forward.

Follow Through

St. Louis Cardinals
Jeff Curry-USA TODAY Sports /

The follow through, at least for Reyes, is not an issue for arm injury.  It is still important.  Growing up, pitchers are taught to be ready to field a ground ball back at them after they release the pitch.  It gets a little more complicated than that, but not much.

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This picture shows the one major flaw in Reyes’ follow though, which is that he favors the first base side during delivery.  He is steady on that plant leg, but he is about to fall over to his left side.  That is because he pulls off to that side on the turn, meaning his center of gravity transfers from the middle of his body to the glove side.

As far as having a successful follow through, the other major component is the placement of the throwing arm.  If a pitchers arm is finishing on the glove side of his body, like Reyes, then there is nothing to worry about.  But if the arm is landing in between the legs, there can be some arm problems along with that due to the arm path of the pitch.


Based on his current mechanics, there is a fairly high re-injury risk for Reyes’ arm.  There is a lot of stress being put on his arm every time he pitches the ball.  Coming off of Tommy John surgery, something in his mechanics will change.  He won’t have to lose his velocity or movement to have a healthier arm; he just needs to figure out what he can change to lessen the stress to his elbow and shoulder.

Next: Recovery Outlook For Reyes

Pitching mechanics are subjective.  There are an endless amount of ways to deliver the ball, and there is always something new that can safely add velocity.  What actually causes injury can be debated endlessly.  In the case of Reyes, when isolating the different parts of his delivery, there is definitely room for improvement.