The Backend of the Cardinals Bullpen is Flying High

Ryan Helsley, JoJo Romero, and Andrew Kittredge have been lights out.

Over the last several years, the Cardinals have struggled to develop impact arms at the major league level. I’ve been critical of it in the past, but so have actual members of the media and even President of Baseball Operations John Mozeliak.

But, for once, I’m not here to talk about the Cardinals’ shortcomings on the pitching side. The team has jumped back up to second place in a weak NL Central, currently hovering around the .500 mark. While the offense has been the cause of that surge, the backend of their bullpen is the reason they aren’t still 10 games under .500.

With Andrew Kittredge in the 7th, JoJo Romero in the 8th, and Ryan Helsley in the 9th, the Cardinals don’t give up much late in close games. The trio has a combined 2.27 ERA, the fourth-best backend trio in baseball. Not only is the performance exceptional, but the Cardinals have used their three best relievers better than anyone else in the sport.


The Elite Usage


These are the Cardinals’ setup men and closer, and the Cardinals take that to heart. Ryan Helsley was involved in every single one of their first 16 wins (which took until May 12th). Sure, if they were winning more frequently, they wouldn’t be able to go to Helsley this frequently (nor if they were winning big), but they came across 13 save situations and needed him accordingly. All three pitchers rank at the top of save & hold leaderboards, showing the lack of diversity in high-leverage opportunities for other Cardinal relievers.

Helsley leads baseball with 19 saves, JoJo Romero leads baseball with 18 holds, and Andrew Kittredge is third with 15 holds. The two setup men combine for 33 holds, and the next closest team duo, Yennier Cano and Danny Coulombe of the Orioles, only have 23 combined holds.

Overall, the Cardinals rank 2nd in baseball with 64 saves + holds (SOLDs), trailing only the Guardians. However, the Cardinals get more SOLDs from their top three relievers than anyone else. 81% of the SOLDs have been by their top three SOLD-getters. The teams immediately trailing the Cardinals, such as the Rangers (78%), Mariners (78%), and Braves (76%), have an average of 39 SOLDs. It’s ridiculous how many SOLDs the Cardinals’ pitchers have, especially considering that three pitchers are responsible for most of them. For reference, the legendary trio of Kelvin Herrera, Wade Davis, and Greg Holland only made up 65% of the 2015 Royals’ SOLDs.

The three pitchers have significantly better results than the rest of the bullpen: the trio has a combined 2.27 ERA and 1.03 WHIP, compared to a 4.50 ERA and 1.46 WHIP from the rest of the bullpen. The 2.24 ERA difference is the second-biggest in baseball, only trailing the Nationals.

Top 10 Bullpens by Difference in ERA from Top 3 SOLDs Pitchers and the Rest of the Bullpen

The Cardinals have three relievers that are above the rest of the bullpen, and they’re getting the most bang for their buck.


The Elite Arms


The trio all have different paths to their success, which is an organizational success by the Cardinals. Ryan Helsley was drafted in the 5th round of the 2015 draft, projecting either as a dominant reliever or mid-rotation starter. JoJo Romero had a career 7.89 ERA with the Phillies (and the infamous Red Bull can smash) and was traded for Edmundo Sosa in 2022. Andrew Kittredge had an outstanding 2021 All-Star season and was traded from the Rays for Richie Palacios after several effective years as a reliever.

Though many bullpens are made up of misfits and outlier arms, the Cardinals have rarely assembled a bullpen as strong as this one, featuring both various trade acquisitions and homegrown talent. Their recent dart throws on free agent relievers (Brett Cecil, Greg Holland, and Andrew Miller) have been underwhelming, while the lone standout impact trade acquisition was Giovanny Gallegos.


The 7th Inning


Kittredge has been the secondary setup man for the Cardinals, often being deployed for the right-handed heavy segment of close games in the 7th and 8th innings. He throws a sinker/slider combo and has a fastball for the occasional lefty, but the reliance on the slider has become massive this year.

For the first time since 2018, Kittredge is throwing the slider significantly more than half of the time. He excels at throwing the pitch down-and-gloveside, resulting in a 49.1% chase rate (94th percentile) and 24.2% SwStr% (89th percentile).


The sinker is mostly used early in the count to get to the slider, which is when Kittredge can cook. He’s got a 3.13 ERA that ERA estimators somewhat agree with and a 25.8% strikeout rate. These numbers are in the career norm for Kittredge, who’s currently proving he’s still healthy after Tommy John surgery took him out of parts of 2022 & 2023.


The 8th Inning


Romero has been the go-to setup man for the Cardinals, as he’s emerged as a dominant reliever who can depose lefties and righties alike. Romero has always succeeded against lefties (career .242 wOBA against) but previously struggled to suppress righties (.351 wOBA coming into this year).

This year, righties have a .248 wOBA against Romero. Romero has a sinker, slider, changeup, and fastball. Since coming to the Cardinals, he’s moved away from throwing his fastball vs. righties. Specifically, this year, he’s turned changeup usage into slider usage vs. righties as well.

JoJo Romero Usage vs. Righties and Overall Stats by Year

Romero’s slider is by far the best pitch in his arsenal, grading out at 113 Stuff+ (no other pitch is above 80). Rather than trying to tunnel his pitches to righties (starting in the same location, then breaking off), he’s throwing them all down and in. While the changeup and sinker are still getting hit, it allows the slider to get a whopping 41.3% CSW%, built on almost equal parts called strikes and whiffs.

Against lefties, he’s a classic sinker/slider guy, throwing the slider 47% of the time. He uses the sinker to get called strikes and lets the slider miss bats. Romero also has the fastball that he deploys as a tertiary weapon (16% usage) to catch a hitter off guard as well. Lefties are hitting to the tune of just a .192 wOBA this year, making Romero the 16th-best lefty-on-lefty reliever in baseball.

While the 1.30 ERA is unlikely to stick, ERA estimators still have Romero around the 2.40 mark, which would be an exceptional year for the 27-year-old.


The 9th Inning


And to close with Helsley, the Cardinals closer jumped into the role in 2022, taking the job from Giovanny Gallegos mid-season. His velocity jumped from around 97 mph in years prior to 99.6 mph, and he’s been above 99 since, even touching 104 in Jordan Hicks-esque fashion. Helsley complements the fastball with a wipeout slider that he relies on more than ever and a curveball for lefties. He uses the fastball and slider equally now, something he’s never done in his career (there was a 20-point difference between the two in 2023).

The new usage seems to indicate a new process: throw strikes and see what hitters can do with a 100 mph fastball and 89 mph slider.

Ryan Helsley’s 2023 vs. 2024

He’s not striking out as many batters, but he is more efficient and throwing more strikes. His 13.4 pitches per inning rank 17th among all relievers (minimum 25 batters faced), which could align with the team’s desire for him to maintain health throughout the year. All of the ERA estimators agree with the 2.5-ish ERA performance, suggesting that this new approach could be here to stay.


All stats included are through June 1st.

Nate Schwartz

Nate is currently writing for the Going Deep team at Pitcher List. He is a lifelong St. Louis Cardinals, devil magic, and Matt Carpenter salsa supporter. You can follow him on Twitter/X/whatever @_nateschwartz. Left-handed pitchers make him happy.

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