St. Louis Cardinals: Carlos Martinez and his new “slider”

The St. Louis Cardinals may not have gotten the best start from Carlos Martinez last night, but the fiery righty did debut a change to his slider.

On Tuesday night, the St. Louis Cardinals opened up the road portion of their 2020 schedule with the first of a two-game series against the Minnesota Twins.

Though the team learned some bad news about Miles Mikolas before the game, the attention was on the starter for the Cardinals, Carlos Martinez.

Martinez made his first start since July 30, 2018, and had some noticeable jitters on the mound. While the righty skated out of a bases-loaded jam in the first inning, he gave up five runs in the second, then was lifted from the game after a solo shot from Twins’ third baseman Josh Donaldson with two outs in the fourth inning.

As the pitcher on the Cardinals with the best raw “stuff,” it’s no surprise that when Martinez is on, his slider is dirty. The six earned runs Martinez gave up against a top-three offense in baseball isn’t how he wanted to start 2020, but I want to talk about something new we saw from Martinez.

While I wouldn’t say that Martinez was on top of his game last night, he did debut a reshaped slider.

A brief physics talk

I am currently going into my senior year in Aerospace engineering, so the underlying physics of a baseball’s motion is something I’ve learned a lot about. The reason why baseballs curve in flight is due to an effect called the Magnus effect. Basically, it says that when a cylinder rotates in a fluid, it generates lift perpendicular to the flow of the fluid. In this case, the “fluid” the baseball is traveling through is air.

When you talk about a ball flying from the pitcher’s hand to the catcher, the spin rate is often cited. In a vacuum, a higher spin rate just means that the ball is going to be generating more lift (or movement, in this case) in the direction of the spin. That ignores both drag and gravity though.

From a physics standpoint, the seams on a baseball are there for the same reason the dimples are on a golf ball. Both “trip” the airflow in the boundary layer of air around the ball causing turbulent (and higher energy) flow. This turbulent flow keeps the stream of air attached to the ball longer, lowering drag.

As soon as the stream of air detaches from the baseball, there is a dramatic loss in lift and the ball stalls soon after. That is why a golf ball with dimples travels almost twice as far as one without. However, it matters a great deal what direction the spin is in and the efficiency that it is thrown with. To avoid turning this all into one big physics article, I recommend anyone who is interested go read this article from Driveline Baseball.

Back to baseball.

The 2019 slider

In 2019, Martinez had a great year coming out of the bullpen. He bumped up the slider usage from 2018 from 22% to 28%. While the usage went up, the effectiveness stayed about the same. Consistently, the 86 mph slider sat at a 40% swing and miss percentage.

Digging deeper, Martinez’s slider averaged 2144 rpm of spin and sat on a 112-degree spin axis. For reference, a 112-degree spin axis is about 9:45 on an analog clock. The spin efficiency on this slider was around 47% and using the BallR Lite tool from Baseball Cloud, we can visualize what this pitch looks like as it leaves Martinez’s hand.

With this design, Martinez averaged 8.03 inches (glove side) of dragless horizontal movement and -30.62 inches of dragless vertical movement with gravity added. When that pitch was on, it looked a lot like this slider Martinez struck out Eugenio Suarez on.

The 2020 slider thus far

Carlos Martinez did only make his first start of the year on Tuesday night, but fans got a look at a slider that was a lot different than what he showcased in 2019. Against the Royals in the pre-2020 scrimmage, we saw a slider from Martinez close to what we saw in 2019.

However, the pitch Carlos was throwing on Tuesday was very different than the above. From BrooksBaseball.net, we know that Martinez was throwing a slider that had a whopping -37.87 inches of dragless vertical break and 10.95 inches of glove-side run. This slider was so far off normal that Statcast registered it as a curveball. This change primarily came from one thing: a change in axis.

Instead of throwing from that ~110-degree mark he used in 2019, Martinez dropped the spin axis to just below 85 degrees. On top of that, Martinez was throwing this slider at 81 mph rather than the 86 mph he sat at last year.

The drop in velocity is consistent with an overall drop in velocity over all of his pitches, but it does make a difference. On a spin axis of 85 degrees (an 8:50 tilt), the lift generated by the 2156 rpm delivery is directed more in the horizontal direction than the vertical direction. Because of this, the Magnus effect “pulls” the ball farther to the glove side and with less lift opposing gravity, the ball drops more.

On Tuesday, Martinez’s slider was nearing slurve territory.

Martinez bumped up the usage of that pitch even more to above 31% and saw mixed results. Throwing the pitch 23 times, Martinez got a swing and a miss just 16.7% of the time. There’s more to just the pitch involved with getting a swing and a miss, but that is much lower than you’d want.

On average, the exit velocity on Martinez’s slider was a respectable 85.7 mph. Of the four times that Martinez gave up hits on that pitch with an EV of above 90 mph, two were missed locations (this pitch to Max Kepler and this one to Eddie Rosario) and the other two were relatively harmless ground balls.

In my opinion, Martinez’s best pitch of the night came on this slider to Miguel Sano in the third inning.

The only other thing to worry about is how much Martinez seemed to have the pitch back up on him last night. A front door slider isn’t always bad, but they are easier to hang when they are thrown front door.

If you look back over Carlos Martinez’s career, his slider on Tuesday has been most similar to his slider in 2015. In that year, the slider averaged a 79-degree axis of rotation with -33.69 inches of dragless vertical movement and 9.87 inches of dragless horizontal movement. That pitch tracked as a curveball as well but still was thrown close to 86 mph.

What does this all mean?

For Martinez, his breaking ball is just one part of his arsenal. If he can’t lock down sequencing and the control of his other pitches, it doesn’t matter how good his slider is.

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One thing we know for sure is that the pitch was completely different on Tuesday than what we have seen out of Martinez before. The pitch velocity and lack of swings and misses with it are slightly troubling, but returning to his 2015 design may not be a bad idea. Batters hit just .172 on the pitch back then and 2015 was arguably Martinez’s best year in the MLB thus far.

We need to wait to see after another start or two whether or not this change to his slider was intentional or just because of bad mechanics on Tuesday. Every small thing has an effect on how a pitch comes off a pitcher’s hand.

While he hung a few sliders, none were hit for extra bases in his first start. If I’m Martinez, I am going to keep throwing that pitch the same way moving forward.

Martinez’s return to the rotation was less than triumphant, but if this new trend sticks with his slider, it is a valuable weapon for the righty to employ.