Randy Rodríguez Is for Real

Have you seen all the technological advances taking over pitching in recent years? High-speed cameras, pitching labs, weighted ball training, wind tunnels – maybe the reason we haven’t sent anyone to the moon for decades is that we’re using all the technology to strike batters out instead. Clearly, the arms race (get it?) favors technological savvy and complicated, inscrutable mathematical modeling.

Here’s a counterpoint, though: Maybe you should just throw a fastball and a slider and laugh as batters flail at both. Case in point: Randy Rodríguez has been the best reliever in baseball this year, and there’s nothing fancy about his game. He throws a 98-mph fastball. He throws a tight slider. That’s it – and that’s really all he needs anyway. Through eight appearances this year, he has 13 strikeouts, zero walks, and zero runs allowed.

Oh, two paragraphs don’t make an article? Well then, I guess we should expand on everything a bit. First, his backstory: Rodríguez signed with the Giants in 2017 out of the Dominican Republic and then slowly climbed the minor league ranks. He was a reliever right from the jump, with only occasional dalliances with short-burst starts, and he got a taste of Triple-A in 2022, where he got shelled. He tried it again in 2023 with better results, and by 2024 he looked like he belonged. That was his first year in the upper minors with a single-digit walk rate, and that’s all the Giants were waiting for; they called him up midseason and plugged him into the bullpen.

Wildness often comes with the reliever territory. Starters are consistent and smooth; relievers are herky-jerky and max effort. That’s not universally true – Mariano Rivera’s delivery could put babies to sleep – but it’s a good rule of thumb. I’m not a kinesiology expert, but Rodríguez’s delivery certainly looks complicated enough to create some wildness. He’s got a leg kick, some torso rotation, a long arm swing, and even a bit of crossfire. Here’s his first fastball of the year:

Were you surprised to see that pitch sail high? I wasn’t. But Jeimer Candelario was; he almost swung at that clear ball. That’s because Rodríguez’s fastball is downright electric. Sure, he has to swing a lot of body parts to generate that electricity, but it pays off in uncomfortable swings and awkward takes. You shouldn’t be able to throw a fastball on this trajectory and land it for a strike:

I’m not telling you anything you haven’t already heard when it comes to good four-seam fastball shape. Remember all those technological advances? They’ve shown us that high induced vertical break, shallow vertical approach angles, and unexpected movement from a given arm slot are all supremely valuable. Rodríguez’s heater dips between two and three inches less than you’d expect given his arm slot and velocity. And that combination is, itself, quite rare. So far in 2025, 195 pitchers have thrown at least 50 four-seamers. Only eight release the ball from a lower height with a higher release point. In other words, he’s releasing the ball from where sidearmers do but throwing from a high-three-quarters arm slot.

How, exactly? It helps that he’s only 5-foot-11. It helps even more that he takes a huge stride as part of his delivery. The bigger the stride, the closer to the ground your torso gets at release, which allows for higher arm angles even with low release points. It’s the kind of delivery that a computer program would dream up.

Oh yeah, our computer programs love it. PitchingBot thinks it’s one of the 15 best four-seamers in baseball, a clone of Ryan Helsley’s fastball more or less. Stuff+ thinks it’s even better than that. The big change this year is command. That’s tough to define, of course, but here’s a blunt way of thinking about it. In two-ball counts, Rodríguez threw his fastball in the zone 52% of the time last year. That’s quite bad; league average is 58%, and the pitchers who hit the zone that rarely and still excel are mostly starters who don’t fear three-ball counts as much as relievers do. This year, his in-zone rate on fastballs in two-ball counts is up to 62%. That’s necessary for a guy who, even now, is prone to sail a fastball or two.

Will Rodríguez keep up his perfect 0.0% walk rate? Obviously not. I don’t even buy him as having plus command. An eight-game sample doesn’t outweigh a mountain of contrary evidence. Sure, he’s improving over time, but improvement from his 2024 form would be an average walk rate, not Logan Webb-level command. In my head, his fastball is a 70 stuff/50 command on the scouting scale. It won’t always be in the right place, but when it is, it’ll look like this:

Hey, that’s nice. But that’s “nice fastball” nice, not “zero ERA zero FIP” nice. The real key to Rodríguez’s success is his “secondary” pitch, which I put in quotations because he’s thrown each exactly 50% of the time this year. That’s a mutant slider, somewhere between gyro and sweeping, that turns batters into uncoordinated nincompoops:

Compared to what’s good in fastballs – speed, shape, angle – it’s harder to explain what makes a slider good in a few words. But it’s easy enough to explain why Rodríguez’s is good: It moves more than a gyro slider but gets to home plate faster than a sweeper. That combination – plus the fact that he’s pairing it with an elite fastball – leaves hitters discombobulated regularly. How regularly? How does a 22% swinging strike rate sound?

Yeah, that’ll do. So will a 56% (!!!) chase rate. So far this year, batters have only swung at 58% of his sliders in the strike zone. You could blindfold them, in other words, and they’d do about as well at figuring out which ones are good to hit. The slider might grade out ever so slightly worse on our pitch models, but it still registers as easily above average, and my eyes tell me the same thing. That slider from a guy who throws 92? Pretty good, honestly. That slider with Rodríguez’s level of octane? Fearsome.

To be fair, I should tell you that the chase and zone swing rates are misleading. That’s because Rodríguez trusts his slider so much that he throws it frequently when he’s behind in the count. He doesn’t quite pitch backwards, but at the very least, he pitches at a slant:

It’s been working so far. Hitters assume that a guy with a reputation for wildness will use his fastball in the strike zone at the first sign of trouble, but Rodríguez flips in bendy stuff and confounds their tendencies. I don’t know if he’ll get away with it forever, but batters are decidedly unprepared for this.

Now, I wouldn’t normally recommend a steady diet of 1-0 sliders for a guy with a career walk rate in the double digits. But what can I say? Rodríguez has the pitch on a string this year. When he’s behind in the count, he spots the slider in the strike zone 70% of the time. Small sample? Absolutely, it’s only 17 sliders. But that’s elite territory, where true command artists live. No wonder he’s not walking anyone – he’s pitching like Bryan Woo when he gets behind in the count.

Is all of this going to continue? Obviously not. That’s just not how baseball works. But I feel confident in saying that so far this season, Rodríguez is pitching like he’s one of the top five or so relievers in the game. It’s not smoke and mirrors. It’s not batters taking pitches down the middle for inconceivable strikeouts. The numbers say that Rodríguez has been one of the best pitchers in baseball this year – whether you’re looking at ERA or diving deep into the weeds.

By the way, that introduction I sold you about ignoring pitching development and keeping it old school? It was nonsense. Old school and new school would say the exact same thing about Rodríguez. Ask any scout who saw him in the minors, but don’t let them look at their laptops or their Synergy Sports accounts, and they’d say “Great stuff, needs to learn command.” Ask literally an algorithm what he looks like this year, and it would say “Great stuff, learned command.” That’s what our two say, at least. So will Rodríguez continue to be the best reliever in the game? Probably not. Things always change, no one stays on top forever, and I can’t imagine him continuing to command the ball this well. But is all of this a fluke? Definitely not. He’s been exactly as good as his two dominant pitches and pinpoint command would suggest.

All statistics current through April 14.