The Cardinals Are the Best Trade Partner for the Red Sox's Bullpen Needs

As the trade deadline draws near, the Boston Red Sox still have a few holes they need to plug before declaring themselves a legitimate playoff-caliber team. There have been a few teams around the league that have signaled that they are open for business, hoping to take advantage of a sellers market. The St. Louis Cardinals are one of those teams, per The Athletic’s Katie Woo, who specifically mentions a handful of Red Bird relievers that could be dealt over the next few days. As luck would have it, the Red Sox have a pressing need for bullpen arms.

The Cardinals have a plethora of relievers that should be of interest to the Red Sox. The Cardinals have underperformed for most of the season, but their bullpen has been fairly consistent when called upon. We’ve highlighted a couple of their arms here at Talk Sox over the last few weeks, so instead of writing individual pieces over each one, I decided to put together an overview for those who may not be as familiar with the available options. Many of their arms are on expiring contracts.

Ryan Helsley, RHP

We’ve covered Helsley quite a bit over the last few weeks, so I won’t spend a ton of time here, but adding him to the bullpen would solidify the backend more than most other relievers on the market. If the team decided to give Aroldis Chapman some more days off — and after his back tightness on July 27, that should be in consideration — Helsley would be able to come in and close the door just as well. Should the team entertain trading Chapman, then Helsley would be the closer for the remainder of the season, and he should be locked into a long-term deal to remain the closer in Boston for the foreseeable future. He’s on an expiring contract and would only be owed a fraction of his $8.2 million salary. He also has one of the coolest entrances in the game and it would be even better at Fenway.

Phil Maton, RHP

Maton is a bit of a journeyman reliever, playing for five teams since he debuted in 2017. He works with a four pitch mix: a curve, cutter, sweeper, and sinker. He features his curve and cutter more than the other two offerings. So far in 2025, he’s sitting on a 2.35 ERA with 48 strikeouts over 38.1 innings pitched. Where he’s shined this season is in his strikeout rate, 30.4%. He isn’t a ‘blow you away’ type of pitcher, but he gets swing and miss with each of his pitches. His exit velocity is in the 99th percentile of MLB relievers, and his expected stats all range in the top four percent as well. He’s notched 20 holds on the season, so he can slot in as an eighth inning set-up man to give the closer a clean inning before they have to enter the game. He’s proven to be incredibly dependable this season and would allow some of the Red Sox’s relievers to slide down in the pecking order, giving them fewer high-leverage situations to sweat out. Maton will become a free agent at the end of the season.

Steven Matz, LHP

Like Helsley above, Matz has been covered here on Talk Sox a bit in recent weeks. The biggest flaw with Matz is that he’s left-handed and the Red Sox currently already have three southpaws in their bullpen. There likely isn’t room for another one, especially one on an expiring contract. If there’s belief within the system that Matz could be converted back into a starter, then he could be worth a look, but that kind of transition may be better suited for the offseason, rather the middle of a successful campaign. Matz is hanging onto a 3.23 ERA currently and has posted 46 strikeouts over 53 innings pitched. Like Helsely and Maton above, Matz will be a free agent at the end of the season.

JoJo Romero, LHP

Like Matz above, Romero is a left-handed reliever. The difference here though, is that Romero is still under team control for two more seasons. He operates as a set-up man for the Red Birds and brings an energy to the mound that is hard to match. No matter the situation, Romero is pumped to get outs. He comes off the mound screaming after strikeouts and struts around with the swagger of someone who belongs on a contending team. He’s currently sporting a 2.12 ERA with 34 strikeouts over 34 innings pitched. He’s a slider-first pitcher with a sinker, changeup, and four-seamer in his back pocket. His expected stats all rank in the top seven percent of MLB relievers, a stark improvement over last year. 

He sports a 24.1% strikeout rate to go along with a 52.9% groundball percentage. With the recently-improved defense of the infield, Romero could make a huge impact coming out of the 'pen. Acquiring him would likely mean some roster manipulation with Justin Wilson or Brennan Bernardino (or a trade of Chapman), but Romero could be a long-term improvement over the current crop of relievers.

The St. Louis Cardinals have four impact arms that the Red Sox should at least kick the tires on as the trade deadline approaches. While Matz isn’t a perfect fit for the bullpen, the other three all could become high-leverage arms in Boston. The Red Sox are just a couple of trades away from being legitimate contenders as October draws near, and this trade deadline could set them up in the bullpen for years to come.