Michael Pineda's slider is key to recent success

The 2016 season has not fared well for New York Yankees right-hander Michael Pineda. After a strong spring training, he embarked on a disastrous regular season campaign. Every time Pineda took the mound he somehow found new ways to lose games. It was clunker after clunker after clunker. Things cratered on May 28th, when Pineda gave up six runs in 3.2 innings against the Tampa Bay Rays. He exited the game with a 6.92 ERA (4.62 FIP), the worst mark among qualified pitchers.

Following the meltdown in Tampa Bay, Yankees General Manager Brian Cashman acknowledged that Pineda's rotation spot was in jeopardy. "He's going to have to do better or we're going to have to make some changes there," said Cashman. Rather than letting the downward spiral continue, Pineda did what he had to do to keep his job. He pitched better. Over his last three starts, Pineda has managed a 2.89 ERA. He also has lowered his season line to a 5.88 ERA (4.05 FIP).

What explains this improvement? Pineda told reporters that he and pitching coach Larry Rothschild worked on mechanics. He credits a changed arm angle with giving his pitches more bite. Yankees catcher Austin Romine explained that with the revamped arm slot, "...he's able to throw the ball down in the zone and repeat it, and his slider has more depth to it." There has been discussion of a mechanical adjustment, but is it noticeable? A comparison of two sliders should give us a better idea.

Let's begin with one of Pineda's hanging sliders. This one comes against Salvador Perez of the Kansas City Royals on May 11th:

Now here's a slider from June 7th against the Los Angeles Angels of Anaheim:

Those pitches have two dramatically different results, don't they? One yields a three-run home run, the other whiffs Carlos Perez. If you look close, you can see that Pineda has lowered his arm angle. This could explain what is generating a deeper break in his slider, instead of hanging it over the plate.

The lower arm slot passes the eye test. But how are the results? Effective sliders miss bats. With the new arm angle, Pineda's slider has been doing just that. Take a look at his whiff percentage for the month of June (courtesy of Brooks Baseball):

Brooks Baseball

Pineda's slider whiffed 22.75% of batters during May. Once the calendar flipped to June and he lowered his arm slot, that number jumped to 33.05%. That's a pretty dramatic increase. His slider is generating swings-and-misses at a much higher rate than it has all season. Pineda lives and dies around the strike zone. If he can get batters to whiff at his slider, than he is far more likely to have a strong outing.

At this point, Pineda is essentially a fastball/slider pitcher. The new arm slot seems to have improved both, but especially his slider. Can other variables explain Pineda's resurgent pitching? Sure they can. Having the General Manager publicly state that your job is on the line could amp up the adrenaline. Remember, Pineda has essentially been pitching for his rotation spot. Nobody wants to go down to Triple-A because of ineffectiveness. That said, we can't measure those intangibles. All we can rely on is the video and data, both of which tell us that the modified arm slot has made Pineda's slider a tough pitch to hit.

If the Yankees are going to claw their way back into the playoff race, they're going to need Pineda to build off this recent success. He is an integral part of the rotation, especially with Luis Severino getting his command ironed out in Triple-A. While the 2016 season had a nightmare beginning for Pineda, the mechanical changes and sweeping slider bode well for a strong second half.