Miami Marlins Reliever Carter Capps Has an Illegal Delivery

Hitting a baseball is probably the hardest thing to do in sports. Giving a pitcher an unfair advantage makes hitting nigh impossible. Justin Gorman demonstrates why Miami Marlins reliever Carter Capps has an illegal delivery that helps make his pitches so difficult to hit.

One of the emerging statistics in pitching is perceived velocity, where a pitcher’s velocity may appear to be higher due to certain elements of their delivery. Alex Speier of the Boston Globe (with a nod to Ian Browne of covered the topic of perceived velocity in the July 8th edition of the Globe.

Speier also mentions that Major League Baseball clarified in April of this year that Carter Capps has a legal delivery. This decision enabled Capps to now hold the highest perceived velocity in the league. He has used that advantage to dominate hitters, to the tune of a 1.34 FIP and 1.13 xFIP while striking out an otherworldly 17 per nine innings.

Questions about his delivery arose early in the season when Capps was pitching for Triple-A New Orleans. His first two pitches were ruled to be “illegal pitches” and thus called automatic balls. When Capps subsequently contacted MLB, he summarized their guidance to him:

“They just said they wanted me to make sure I dragged my foot and not get too elevated in the air, and make sure it’s more on a lateral plane… as long as I do that, they have no problem with it.”

While MLB has apparently opined and determined that Capps’s delivery is legal, there is nothing in the official MLB rules that corroborates the reasons given above. In fact, a close look at the rule book shows no evidence to back up the reasoning MLB gave to Capps.

According to rule 5.07, there are two legal pitching positions – the Windup Position and the Set Position, often referred to as the stretch. In both cases, there is great emphasis given to the rubber (also referred to as the pitcher’s plate) being an integral part of a legal pitching delivery. In both pitching positions, pitchers “shall take signs from the catcher while in contact with the pitcher’s plate.”

Beginning with the Windup Position, the rule states in relevant part that the “pitcher is permitted to have his ‘free’ foot on the rubber, in front of the rubber, behind the rubber or off the side of the rubber.” This differentiates the free foot from the pivot foot, which must maintain contact with the rubber. The rule also states that the pitcher “shall not raise either foot from the ground, except that in his actual delivery of the ball to the batter, he may take one step backward, and one step forward with his free foot.” (Emphasis added)

The stretch – which Capps throws from most often – is not nearly as explicit with the required activity of either the free or pivot foot during delivery. The rule makes several mentions of the pivot foot while setting up for delivery:

Capps Set Position

“Set position shall be indicated by the pitcher when he stands facing the batter with his pivot foot in contact with, and his other foot in front of, the pitcher’s plate, holding the ball in both hands in front of his body and coming to a complete stop. From such Set Position he may deliver the ball to the batter, throw to a base or step backward off the pitcher’s plate with his pivot foot.”

Based on the two positions, Capps gets a distinct advantage by throwing exclusively out of the stretch. If he were throwing from the Windup Position, the argument is very strong that his hop-step delivery would be illegal based on the definition above. Even from the Set Position, it could be argued that Capps does “not deliver the ball to the batter” with his “pivot foot in contact with… the pitcher’s plate”. Capps hops away from the pitcher’s plate and then delivers the ball. MLB could have easily interpreted his delivery as a violation of this rule:

Capps 2015 Delayed Arm Action

Fascinatingly, the rule book does not mention the most controversial elements of Capps’ delivery, neither regarding an elevated hop nor dragging feet laterally. That being said, in both descriptions the rules reference “any natural motion associated with his delivery of the ball to the batter.” There is a theoretical argument that Capps (and fellow hop-pitcher Jordan Walden) could be engaging in unnatural motions.

However, the more compelling argument against Capps’ unorthodox delivery would be the actual dimensions of an MLB playing surface:

2.04 (1.07) The Pitcher’s Plate

The pitcher’s plate shall be a rectangular slab of whitened rubber, 24 inches by 6 inches. It shall be set in the ground as shown in Diagrams 1 and 2, so that the distance between the pitcher’s plate and home base (the rear point of home plate) shall be 60 feet, 6 inches.”

Across all professional sports, measurements are the great equalizer. Referees will take official timeouts and measure first downs with chains in football; the NBA rulebook specifically states the parameters of the thread count of the regulation net. While MLB teams have the ability to get creative with ballpark dimensions (within the limits established under Rule 2.01), the lengths of each base path, as well as the distance from the mound to home plate are set in stone.

Throughout the history of America’s Pastime, pitchers have set themselves apart by developing unique windups and deceptive deliveries. Luis Tiant turned to face second base during his windup; Chad Bradford nearly scraped his knuckles on the dirt throwing a submarine delivery; Paul Byrd would swing his arms (sometimes more than once) before a pitch to throw off a batter’s timing.

Alternatively, pitchers will commonly employ longer strides resulting in a release point closer to home plate, which would increase their perceived velocity.  It does come more naturally to taller pitchers, like Randy Johnson, but is not impossible for those of shorter stature. Tim Lincecum, a full foot shorter than the Big Unit, has a stride length of 129% of his height, compared to the average of 77-87% of a pitcher’s height.  His increased perceived velocity may have had a significant impact on Lincecum’s back-to-back Cy Young Awards as his stride – grossly disproportionate to his height – resulted in a much higher relative perceived velocity.

As comparisons go, there may not be a better example than Aroldis Chapman, the closer for the Cincinnati Reds. The Cuban Missile stands 6’4”, has a stride that averages 120% of his height, and combines those physical attributes with an absurd amount of upper-body torque, as described in this Sport Science video. Chapman routinely throws with triple-digit velocity and has been clocked as high as 105 mph. He accomplishes this through effective mechanics that result in a release point closer to home plate than the average pitcher. However, he does so while barely moving his pivot foot away from the rubber:

Capps vs Chapman Sync

The difference between the above examples and Capps is that none of them broke the letter of the law – they gained advantages through altering their mechanics within the rules. Look at the difference between Capps in  2013 (4.73 FIP, 3.56 xFIP, 10.1 K/9) on the left, Capps in 2014 (2.35 FIP, 3.10 xFIP, 11 K/9) in the center, and Capps in 2015 (1.34 FIP, 1.13 xFIP, 17 K/9) on the right: 

Capps Comparison IMG 1

This above image clearly shows the evolution of his throwing motion as he transitioned from a long toe drag rolling over his back ankle in 2013 to a hop step where he continued his arm action during the hop in 2014, to the current version where he hops and nearly finishes landing before continuing his arm action.

Capps was a heavy strikeout pitcher before 2015, but had issues giving up home runs – in 2013 in 53 appearances with the Seattle Mariners (pre-hop) he gave up 12 home runs in 59 innings. Plainly speaking, Capps was not fooling anyone. However, in 2015 with his much higher perceived velocity, he has dramatically reduced his home run rate.

Dan Jennings told Mike Petraglia at, “The one thing you don’t want to do is change a kid’s mechanics and see a kid hurt his arm.” With all due respect to the interim manager of the Marlins, Capps has a fairly severe ankle movement in his pivot foot in 2013, but the hop itself does not appear until 2014 (and it was not used by Capps in all his pitches in 2014 like it appears to be in 2015). To suggest that a switch to his previous mechanics would injure his arm is nonsense – it would likely result in him being a less effective pitcher. It would be a lot easier to view Capps as a sympathetic figure if he didn’t adopt this delivery after struggling in MLB.

While the MLB rule book does not specifically address a hop during a pitcher’s delivery, the argument is still very strong that such hops should be illegal. Major League teams cannot decide to change the length between the pitching mound and the plate, and the players should not be able to either. There are strict rules about the batter’s box, the pitching mound and the base paths for a reason – they are boundaries that are fundamental to the uniformity and fairness of the game.

Carter Capps may have been told by MLB that his delivery was acceptable for reasons that are outside the boundaries of the official rule book, but until MLB affirmatively changes the rules to allow for the hop that both he and Walden employ, it will be a subject of debate. There will always be pitchers looking to develop advantages on the mound, and history tells us that those can be extremely effective while following the rules. Capps needed an advantage to further his career and did so by adding a hop, thus reducing the distance of a hard-and-fast measure in the sport of baseball.  The reason his perceived velocity is relatively higher than every other pitcher throwing legally is because Capps is modifying a critical boundary fundamental to the game. This is a clear violation of MLB’s rulebook.

Follow Justin on Twitter @j1gorman.

*Special thanks to Damian Dydyn for the gifs.


  1. No “vagary,” no technicality. The rules clearly state you are to be in contact with the rubber when you deliver the pitch. “Mockery” is right. Otherwise, why not just take a hop, skip and a jump & deliver the ball from 45 feet?

    Yes, other pitchers do violate the rule by dragging off the rubber before releasing the ball. But Capps shows us that allowing this means allowing … whatever. The rule needs to be either enforced or changed. If enforcing isn’t practical, then you could say, for instance, the pivot foot has to start on the rubber and stay on the ground.