Deep dive into how the Cardinals transformed their bullpen for the 2024 season

The St. Louis Cardinals hoped that they could turn things around in one calendar year after a disastrous 2023 season, but despite winning 12 more games, they failed to make the postseason once again.

Over the next few days, I want to take some time to look at four phases of the Major League roster (offense, defense, starting pitching, and bullpen) and evaluate the changes the club made in each of these areas as well as how much better (or worse) those units were for the Cardinals in 2024.

I wanted to start this mini-series by discussing what was easily their greatest strength in 2024 - the bullpen. What changes did John Mozeliak and the front office make to this group last offseason? Why did it perform differently than the bullpen the year prior? What lessons can the organization learn from how it overhauled their bullpen in just one offseason?

Let's take a look.

Personnel changes

Added: Andrew Kittredge, Ryan Fernandez, Keynan Middleton, Riley O'Brien, Nick Robertson, and Shawn Armstrong (mid-season)

Subtracted: Jordan Hicks, Chris Stratton, Drew VerHagen, Genesis Cabrera, Casey Lawrence, James Naile, Jacob Barnes, Andrew Suarez, and Giovanny Gallegos (mid-season)

Going into the offseason, we knew that the Cardinals were going to have significant turnover when it came to their pitching staff. We'll discuss the rotation next time, but for as much attention as that unit got from fans and media in the Cardinals' retooling efforts, the bullpen was sneakily in equally bad (if not worse) shape and was going to be a crucial part of whether or not the club could get back to winning baseball in 2024.

During the season, the Cardinals traded away Jordan Hicks, Chris Stratton, and Genesis Cabrera, three relievers who were expected to play major roles for the club that season. Hicks clearly had the best season of that bunch and had the most effective year of any Cardinal reliever not named Ryan Helsley. Moving him at the deadline was the right move, but it left a clear hole at the back of their bullpen in the process.

Cabrera was also supposed to be a major part of the Cardinals' bullpen in 2023, but he struggled big time with his control and got beat up to the tune of a 5.06 ERA in his 32 innings of work. Stratton wasn't special by any means, but he was able to cover 53.2 innings for St. Louis, meaning they at least had significant bulk to cover in his case along with losing Drew VerHagen's 61 innings in free agency.

Rather than making some big moves for relievers last offseason, the Cardinals made a variety of trades, free agent signings, and even a Rule 5 selection to bolster their group of arms. Andrew Kittredge was probably the biggest name they acquired, swapping outfielder Richie Palacios in the deal. Keynan Middleton did not appear in a game for St. Louis in 2024 due to injury but was an interesting signing in January as the club looked to round out their bullpen.

Ryan Fernandez and Nick Robertson both came over from Boston, with Fernandez being a Rule 5 selection and Robertson being the "headliner" of the Tyler O'Neill trade. Riley O'Brien, along with Kittredge, Fernandez, and Robertson, all had connections to Chaim Bloom.

Bullpen results in 2023 vs. 2024

In 2023, the Cardinals' bullpen ranked in the bottom third in all of baseball in most major categories. They lacked swing-and-miss, their high-leverage guys were either injured or unreliable, and they lacked the depth needed to make up for their underperforming pieces.

JoJo Romero and John King did stand out in big ways for the club down the stretch though and earned roles with the 2024 club in the process. After Hicks was traded and Helsley was injured, Romero stepped into more and more high-leverage roles, proving to the Cardinals that he could be a weapon for them in 2024. King was a throw-in piece in the Jordan Montgomery deal but was highly impactful in his 18.2 innings for St. Louis in the second half.

Overall though, things unraveled quickly for the Cardinals' bullpen. If 2023 taught the Cardinals anything about their relievers, it was that they lacked the depth of high-leverage arms needed to survive a 162-game schedule, and they needed to get creative with how they went out and got arms to fill those roles. Signing someone to a big deal would likely be a major mistake.

Kittredge and Middleton were brought in do just that, and the mix of Fernandez, O'Brien, and Robertson were meant to be low-risk, potentially high-reward finds that St. Louis could try to find a spot for in their bullpen.

While Middleton was injured all year, Kittredge was that horse at the back of their bullpen the Cardinals desperately needed, posting a 2.80 ERA in 70.2 innings of work this year. Fernandez ended up "hitting" on his potential, posting a 3.51 ERA as he covered 66.2 innings of work. For context, those are more innings than St. Louis lost between the duo of Stratton and VerHagen, but both Kittredge and Fernandez provided much higher-quality outings.

Those two additions, paired with a healthy Helsley and the experience that JoJo Romero gained last season gave the Cardinals four high-leverage arms they could rely on throughout the season.

In 2023, the Cardinals had just one reliever throw over 50 innings with an ERA lower than 4.00 (VerHagen). In 2024, the Cardinals had six different relievers accomplish that feat, with five of those guys having ERAs lower than 3.50 (Helsley, Fernandez, Kittredge, King, and Romero).

While the Cardinals did not really increase their swing and miss like they had hoped they would in their bullpen, they transformed their mediocre group from 2023 into a true strength of the club in 2024. At any given time last season, the Cardinals could really only truly trust one or two arms in big spots. This year, manager Oliver Marmol had the ability to mix and match his arms and deploy a parade of stoppers when everyone was rested and ready to go.

2023 was a mess all around, but Marmol often times had to turn to poor options in big spots when the game script really required a better arm there. The problem was though that Marmol just did not have enough weapons to deploy. 2023's bullpen failures were far more due to the lack of talent than the way Marmol managed that group.

One interesting stat you'll see from the chart is that the Cardinals actually ranked second to last in all of baseball this year in blown saves. How is that a marker of a good bullpen? Well, they did rank first in saves and top ten in ERA, FIP, and WPA, so there is obviously more to that story.

First, something that was well-documented this season was how the Cardinals struggled to win games with a large margin of victory. Oftentimes, the Cardinals were only able to muster a one or two-run lead, forcing Marmol to deploy the best arms that were available that day to secure the win. No reliever is going to shut down an opponent every time though, so the Cardinals' margin for error was razor-thin almost every outing, thus meaning one mistake could cost the Cardinals that game.

Having Ryan Helsley healthy this year was a huge boost for this bullpen though. Helsley threw just 36.2 innings in 2023, securing 14 saves and blowing five while posting a 2.45 ERA. In 2024, that ERA dropped to 2.04, and Helsley threw 66.1 innings while locking down a Cardinals single-season record of 49 saves and blowing just four all season long.

Yes, having a dominant closer season like the one Helsley turned in goes a long way toward having a great bullpen. Kittredge and Romero combined to blow 15 saves, but it is hard to find a problem with the kind of production they offered St. Louis all year long. Had the club's offense been better this year, that blown saves number likely drops significantly.

What can the Cardinals learn from their 2024 bullpen?

To me, if there is one area the Cardinals need to replicate their process the most, it is how they built this bullpen, and I am not just saying that because of the results this year.

Even in the offseason, I was very encouraged by how the Cardinals built up their bullpen mix, as it allotted for the right amount of upside while not taking on significant risk either. Instead of handing out sizeable contracts to relievers as they did with Andrew Miller, Brett Cecil, and Greg Holland in the past, the front office signed or traded for players at a low price point, and did it in bulk.

This is not guaranteed to be successful, but there is a much greater chance of building a strong mix of relievers when you get more "lottery tickets" in your hands, rather than making a big swing for the top guys. While O'Brien, Robertson, and Middleton did not work out for various reasons, St. Louis hit big on Kittredge and Fernandez, which helped take this group to the next level.

While the Cardinals' offense did not do this bullpen any favors, the rotation was a bit better this year, so the length the Cardinals got from their starters more often, and the leads they could hand this bullpen, even if it was small, allowed Marmol to deploy his arms in the best possible way to win each ball game.

Even as the Cardinals are likely to lose Helsley this offseason and possibly Kittredge, the Cardinals' method of building this bullpen can be done again this offseason and potentially produce similar results. Losing Helsley and Kittredge are massive losses, but if we know anything about bullpens in today's game, it is that teams always have to be ready to raise up the next crop of bullpen arms with how volatile the group can be.

There were plenty of flaws with the 2024 St. Louis Cardinals, but their bullpen was not one of them. Hopefully, the front office has figured something out this past calendar year and is able to build and maintain strong bullpens moving forward.