Sandy Alcantara Is Becoming One of Baseball’s Best Pitchers

Sandy Alcantara has taken the next step. Already one of baseball’s better groundball-inducers, Alcantara has added the strikeout to his game in the second half of this season. In the process, he’s transformed from an above-average starter into one who is knocking on the door of ace status.

Over the last three years, Alcantara has been worth 7.2 WAR, a figure that ranks 27th among starting pitchers in that time. It has been volume-heavy value: his 3.94 FIP since 2019 grades out as just slightly above-average (93 FIP-), while his 434 innings pitched ranks ninth among all pitchers. His 21% strikeout rate and 8% walk rate scream nothing special, though his near-49% groundball rate kept the homers off the board.

Up until this season — and really up until its second half — that was Alcantara’s story. He was a very good pitcher, but there was still tantalizing potential he was seemingly leaving on the table. Even from 2019-20, when he struck out less than 19% of the hitters he faced, Alcantara’s average fastball velocity ranked near the top of the majors. Throwing both a four-seamer and a sinker, he averaged 95.7 mph with his fastballs, an 88th percentile mark. He also featured a slider and a changeup that both offered above-average called-strike-plus-whiff rates, suggesting Alcantara could better optimize those pitches for more strikeouts. If he could just strike out more hitters while maintaining his groundball rate, he had the potential to become an elite starter. And over his 12 starts since the All-Star break, that is exactly what has happened:

In the second half, Alcantara has struck out 28% of the batters he’s faced and walked fewer than 5%, all while keeping more than 50% of his batted balls on the ground. He has a 3.12 FIP over 78 innings, making him the 14th-most valuable pitcher in the game since the break. He’s been even better since August 1: with a 2.61 ERA and 2.80 FIP over 69 innings, Alcantara moves all the way up to eighth on the WAR leaderboard in that span.

Where are these strikeouts coming from? It all goes back to the increased use of both his changeup and his slider. After throwing them roughly a one-third of the time combined in both 2019 and ’20, Alcantara has bumped the combined usage to nearly 50% this season. If you look at his full-season stats, it appears that the changeup has seen the bulk of the increase. Alcantara threw it just 12% of the time in 2019 and 10% of the time in ’20 before using it 24% of the time in ’21. Max Greenfield wrote about this notable jump in changeup usage back in June at Pitcher List. He noted how despite the pitch being 6 mph slower on average than his sinker, his changeup has similar movement characteristics, which can rather easily induce whiffs. Indeed, Alcantara has yielded a 17.8% swinging strike rate on his changeup, a 71st percentile mark.

But the changeup hasn’t been the only driver of Alcantara’s second-half success. At the time Greenfield wrote his article, Alcantara’s full-season slider usage was actually down compared to 2020. But now, it’s up. That’s because he has thrown the slider more frequently in the second half. Before the All-Star break, Alcantara threw the slider just 21% of the time, but he’s thrown it almost 29% of the time since. And considering his slider has the highest whiff-per-swing rate of any pitch in his arsenal, it’s pretty easy to see how it has contributed to his jump in strikeout rate.

Just look at Alcantara’s pitch mix in two-strike counts. The changeup usage is still way up compared to 2019 and ’20, but it’s the slider’s usage recovery that has given Alcantara a completely different look. In two-strike counts in 2019, hitters saw a changeup or slider just under 40% of the time. In two-strike counts in the second half of ’21, they’ve seen one of those pitches more than 55% of the time:

This is a very different distribution of pitch usage than what we see from Alcantara in all other counts, where the sinker is much more regularly featured. This intuitively makes sense; most pitchers approach hitters differently after reaching two strikes. But what’s interesting here is that the changeup and slider are no longer just two-strike weapons; they make up nearly half of all his pitches in non-two-strike counts as well. What’s more, his curveball, which has been a wholly ineffective pitch for him this season, has been all-but-removed from the arsenal:

Is that it, then? Did Alcantara simply need to adjust his repertoire to better optimize strikeouts? Well, not quite. While I do think that most of his change is the result of better pitch selection, it’s also worth noting that the pitches themselves have improved as well. His slider, which induced a whiff on just 31.5% of swings in 2019, is now getting whiffs on upwards of 40% in the second half. That 2019 figure put his pitch in the 33rd percentile of sliders. Since the All-Star break this season, however, his slider is generating whiffs at a rate that nearly puts the pitch in the top-quarter of the league. That’s quite the jump.

The changeup is a bit of a different story. Its whiff rate and other pitch-specific metrics actually looked better in 2020 than they do now. Here’s some of the metrics on both the slider and changeup using the same date ranges as above:

How does this compare to the rest of the pitches Alcantara throws? Let’s take a look. Since we’re looking at the combined slider-changeup usage here, I’m going to group the two pitches together into one bigger bucket:

As you can see, Alcantara’s slider and changeup have always outpaced his sinker and four-seam fastball in what I like to call the strike-generation metrics, even in prior years when he did not strike out as many hitters overall. By throwing those two pitches more frequently — particularly in two-strike counts — Alcantara has optimized his mix such that he’s striking a better balance between groundballs and strikeouts.

As a result, Alcantara might be headed for legitimate greatness, and we might have already caught some real glimpses of the future. In what was without a doubt the best start of his career, Alcantara struck out 14 Mets in a complete-game victory on September 8, while reaching 102 mph on the radar gun in the eighth inning. But it wasn’t just that start. Alcantara has a total of six double-digit strikeout games out of his 76 career starts. Four of them have come since August 1. If he can keep this up — or something even close to this, as he’s probably receiving some good fortune in addition to the pure dominance — I have a hard time thinking that Alcantara won’t be considered among baseball’s best pitchers by the end of next year, if not sooner. A small adjustment in his pitch mix might’ve made all the difference.