Sandy Alcantara Sinks His Way to Success

There hasn’t been much to celebrate this year in Miami, but the Marlins starting rotation has been a source of a few positive developments. Caleb Smith and Pablo López started off the season strong but faded in the second half. Zac Gallen and Jordan Yamamoto both made their major league debuts, and while Gallen was shipped out at the trade deadline, Yamamoto has shown some promise as a 23-year-old rookie. But the most exciting progress has come from Sandy Alcantara.

On the surface, Alcantara’s stat line doesn’t look that impressive. His park and league adjusted FIP sits just seven percent above league average but that’s more due to some luck in keeping the ball in the ballpark. His 18% strikeout rate is one of the worst in the majors among qualified starters despite a fastball that sits in the mid-90s. The biggest question mark attached to him as a prospect was his command of his repertoire. In his 42 major league innings prior to this year, he ran a walk rate above 15%. He’s managed to drop that down to 10.7% this year, but that’s still one of the worst walk rates in the majors.

The fourth ranked prospect in the Marlins organization and 127th overall at the start of the season, there were plenty of doubts that Alcantara could stick in a major league rotation as he developed. He’s likely going to make 30 starts this year, which has to be seen as a success for the Marlins player development group, shoddy peripherals be damned. But since the start of August, Alcantara has shown flashes of brilliance, giving Marlins fans another starting pitcher to dream on for next season.

In his seven starts since the end of July, Alcantara has posted a park and league adjusted FIP 19% better than league average. More importantly, his strikeout rate has jumped up to 22.3%, a nearly six point improvement from where it sat after the first four months of the season. The highlight of this stretch came in his last start at home against the Royals. He threw a complete game, holding Kansas City scoreless while allowing just six base runners and striking out eight. That was actually the second complete game shutout he’s thrown this year, his first coming back in May against the Mets.

His game against the Royals was a great example of the adjustments he’s made to his approach and repertoire that have driven his success this summer. Here’s a look at how his pitch mix has changed as the season has progressed:

Pitchers all across the game are ditching their sinkers in favor of riding four-seam fastballs in an effort to generate more whiffs. Instead, Alcantara has gone against the grain and truly embraced his sinker over the last two months of the season. The usage of his secondary pitches has stayed relatively stable throughout the year, so this change is really just swapping the usage of his four-seam fastball for his sinker. Here’s a comparison of the physical characteristics of Alcantara’s two fastballs, and their percentile ranks when compared within each pitch type:

From a pitch shape perspective, Alcantara’s four-seam fastball is rather mediocre. The velocity is nice but it doesn’t have much ride and it doesn’t have much run. But his sinker has a far more interesting movement profile. With nearly the same velocity, his sinker has above average run and sink.

Dan Aucoin of Driveline Baseball recently did some research into how fastball movement relates to pitch quality. The heatmap in the tweet below shows estimated pitch quality based on positive outcomes at a given movement profile:

Alcantara’s four-seam fastball sits right in the middle of that blue circle where fastball outcomes are the worst. But his sinker sits near the edge of the third contour where outcomes are much more favorable. The data backs this up:

For the pitch outcomes above, I’ve taken his raw whiff rates and batted ball rates, compared them to league average rates within each pitch type, and calculated plus scores where each point above or below 100 is a percentage point above or below league average. Alcantara’s four-seam fastball is good at inducing pop-ups but the pitch’s whiff rate is 11% below league average. But his sinker’s whiff rate is elite, sitting in the 93rd percentile among all pitchers who have thrown at least 100 sinkers this year. Simply swapping the usage of his four-seam fastball for his sinker likely went a long way towards that six point increase in strikeout rate.

Here’s an example of Alcantara’s sinker in action:

The natural movement he gets on the pitch makes it a great pitch to throw inside to right-handed batters. In the example above, Whit Merrifield swings right over the top of a perfectly placed sinker. That’s exactly where’s he’s been placing the pitch this year.

The pitch has also helped him keep the ball on the ground a little more often. His groundball rate over his last seven starts is 47.6%, a big improvement over the 43.5% rate he ran over the first four months of the season.

Beyond simply being a more effective pitch, his sinker plays well with the rest of his repertoire. He most commonly pairs his sinker with his hard diving slider, giving him an approach that’s focused on moving the ball side-to-side rather than up and down like you’d expect with a riding four-seam fastball. His slider is easily his best secondary weapon and the pairing of the two has been deadly, particularly against right-handed batters. Righties have managed just a .204 wOBA against him over the last month and a half.

Alcantara has always had electric stuff but struggled to put it all together at the major league level. The changes to his pitch mix since the end of July have seemingly unlocked a new level of performance for him. That’s an exciting development for the Marlins and gives them another piece to build around as they work towards ending their endless rebuilding process.