Jesús Luzardo Didn’t Add a Cutter

It isn’t supposed to be this easy. When the Phillies traded for Jesús Luzardo over the winter, they did so with the understanding that he wouldn’t be an ace right from the jump. He was coming off a rough and injured 2024, he’d only hit 20 starts in a season once in his career, and every warning light you could possibly imagine was flashing – worst stuff model grades of his career, lowest strikeout rate, lowest whiff rate, highest hard-hit rate.

Those warning signs explain why the Phillies were able to acquire Luzardo for relative peanuts. It also explains why our projection systems were unenthused by him heading into this year, projecting a 4.19 ERA, a distant fifth among Philadelphia’s starters. No one doubts Luzardo’s potential, but after six seasons and 500 innings (itself not a great sign) of roughly league-average work, well, at some point you are what you are.

Right, yeah, Luzardo’s been the best pitcher on the Phillies this year and one of the best pitchers in baseball. I’m not as surprised as I thought I’d be. But given that we’re a quarter of the way through the season and his ERA and FIP are both below 2.00, I think it’s time to take a closer look at what he’s doing differently.

First things first: Luzardo added a sweeper. Quite frankly, I’m shocked that he didn’t throw one before. Luzardo’s slider has always been his best pitch. His ability to spin a slider was part of what made his prospect profile so enticing, and he throws it frequently, 29% of the time in his career to date. He uses it like a Swiss Army knife; it’s an out pitch to batters on either side of the plate, a way to steal early strikes, and his best way of getting from one to two strikes.

His ability to manipulate a slider suggested that he’d be a natural with a sweeper, and just as expected, he’s taken to it swimmingly. Here’s what his old, tight slider looks like:

Here’s the new sweeping version:

There’s a 10-inch gap in horizontal movement between those two pitches. Naturally, he throws both now, rather than just one. Why abandon your excellent slider when you can just supplement it? More than half the pitches he’s thrown to lefties this year are sweepers, in fact. That’s a big change for Luzardo, who didn’t have a purpose-built pitch for attacking lefties until he developed this version of his slider. Sure, I showed you a righty there so that you could see both sliders thrown to the same batter with a good camera angle for viewing slider movement, but big, sweeping pitches like that are at their best with the platoon advantage.

The results speak for themselves. Luzardo has faced 44 lefties this year. He’s posted 20 strikeouts and no walks. Out of those 20 strikeouts, 15 have come on sweepers. Yeah, that’ll play. The 2025 version of Luzardo attacks lefties like a high-powered reliever, with huge horizontal separation between his sinker and sweeper and the ability to run four-seamers up in the zone when necessary. It’s the kind of form he always hinted at, but he didn’t quite have the right pitches to fully actualize it.

Last week, I came up with a statistic called adaptation score. It measures the separation between a pitcher’s arsenal against lefties and righties. The Phillies are believers in this style of pitching – look no further than their use of sinkers. That’s not how Luzardo generally pitches, or at least, it’s not how he used to. In 2023, his best year before this one, his separation score was 4.7, much lower than league average. In other words, he used the same two pitches to go after lefties and righties alike. In 2025, that’s up to 17.7, a huge increase. Even that might understate it; he’s now throwing lefties a roughly 50/50 mix of sinkers and four-seamers when he uses his fastball, while righties rarely see the sinking version. His three-pitch adaptation score has ballooned from 13 to 30.9; however you slice it, Luzardo is varying his approach by far more than he did before.

All of this sounds so simple. Just invent a new breaking ball, keep throwing the old one, and profit. What Luzardo is doing is far more impressive than that, though. He’s always been a stuff-over-command guy. He still is, but he’s also improved his command markedly. He’s never run a higher zone rate. He’s never run a lower walk rate. He’s never spotted more pitches on the borders of the strike zone. He’s hitting corners at the same clip as Shota Imanaga and Bryan Woo; in 2023, he was keeping Craig Kimbrel and Jakob Junis company, a much less impressive set of comps.

I’ve written a lot of these “check out the hot month from this pitcher” articles over the years. I generally find that they’re not as good as the recent results would suggest, even if they do have one new pitch that’s driving their improvement. And I mean, yes, sure, that’s true of Luzardo. There’s no way he’s going to keep being this good. His new approach against lefties and new command against everyone explain his improvement. They don’t explain his sudden and unexpected mastery of contact quality suppression, or his sinker going from 50% grounders to 75%.

The truth is, while you can adjust your evaluation of Luzardo based on what he’s done this year, he’s always been capable of stretches of absolute dominance like this. The changes he’s made increase both his floor and ceiling, in my eyes, but they don’t change the key thing we already knew about him: He’s electric, capable of vaporizing batters when he’s at his best.

This year, the level of vapor he hits when he’s at his best appears to be higher than before. Turning lefties into absolute zeroes is a skill that he didn’t have until he added his new breaking ball. Having two breaking balls to keep hitters off balance has been great, too; even though he doesn’t throw the sweeper to righties as often as he does to lefties, he’s using about a 50/50 mix of sharp and sweeping sliders. Pretty much across the board, the changes he’s made this year are helping his bountiful natural talent shine through.

You know the “sprinkle in a cutter” phenomenon that Michael Baumann and I can’t stop talking about? Luzardo has done that in reverse. His old slider performed like a cutter, more or less; it sat halfway in between a big breaking ball and a fastball. The problem is that he didn’t have a big breaking ball, making the slider a bridge pitch to nowhere. He didn’t add something in the middle; he added something that could play off the middle-movement pitch he already had. So while the particulars here are different, the idea is very much the same. Create a broad palette of pitches with some overlap, and hitters will have a hard time figuring out what’s what.

That should be scary for Phillies opponents. And more broadly, that should be scary for hitters. The whole trope about going into the lab to improve your lacking pitch mix? The “lacking” part clearly isn’t necessary here. Luzardo didn’t need to adapt or die, even though he was coming off a so-so season. He already had the great stuff, the nasty breaking ball, the prospect pedigree and easy velo. Neither did Paul Skenes or Logan Webb, two of the best pitchers in baseball, who also went to the lab this winter and revamped their games.

In a lot of ways, it’s the Moneyball era all over again. When the less-well-off develop a new tactic, it’s wonderful. When the A’s and Rays are doing it, it’s darling. When the Red Sox and Dodgers take their turn, the fun’s over. Likewise, when fringe big leaguers and indy ball strivers are hitting up pitching labs to hone their skills, it feels like a plucky underdog story. When the best pitchers in baseball start doing it, the novelty goes away.

So will Jesús Luzardo keep pitching this well? No. But he’s inarguably better than he used to be. The way that he’s changed? It’s coming to a ballpark near you. Perhaps not in the form of Luzardo, perhaps not in the form of the Phillies, but in the form of some top pitching prospect or currently good arm who isn’t satisfied with “good enough.” The spiral of progress is headed ever upward – and now we’re at the part of the climb where the established powerhouses start using the technology that disrupted their earlier prominence. Welcome to pitch design, Jesús. You’re a great embodiment of the trend in addition to being one of the best pitchers in baseball.