Poll: Who’s The Best Rental Reliever Available?

Virtually every contender is on the lookout for bullpen help at the deadline, and this summer should be no exception. The Dodgers, Tigers, Phillies, Yankees, Cubs, and Mets have all been connected to the relief market already this summer, and plenty of other clubs will surely be searching for upgrades to their relief corps as well. An unusual quirk of this summer’s trade market, however, is that the majority of the most frequently discussed names are elite arms controllable beyond the 2025 season. Jhoan Duran, Emmanuel Clase, Mason Miller, David Bednar, and Pete Fairbanks are just a handful of the high-end relievers with multiple years of team control who have found themselves in the rumor mill this July.

Many of those big names likely won’t be moved, however, and the ones that do get traded are likely to come with hefty price tags. For teams with less prospect capital to spend or other areas they’ll need to balance upgrading, perhaps adding rental relief help at a lower price could be a more attractive path to take. Who’s the most interesting pending free agent available to help a contender’s bullpen this summer? A look at some of the options:

Danny Coulombe

Coulombe, 35, has long been one of the better left-handed setup men in the game when healthy. With that being said, for the majority of his career the southpaw has carried a hefty platoon split. He’s a career 2.13 ERA arm against same-handed pitching, but righties have managed to post a 4.14 figure against him over the years. That has limited Coulombe’s abilities as a shutdown set-up man over the years, but he’s changed that narrative with the Twins this year. Not only has he posted a microscopic 0.63 ERA in 28 2/3 innings of work, he’s done so with a 1.23 ERA and a 1.93 FIP against right-handed hitters. Those utterly dominant numbers would be welcome in any contender’s bullpen, though Coulombe’s shaky track record against opposite-handed batters and his small sample of work this year could make him less attractive than his rate numbers would otherwise imply.

Ryan Helsley

Helsley was one of the most talked about trade candidates in baseball for much of last offseason, though the Cardinals ultimately opted to hold onto him. Now that the club appears to be signalling that a sell-off could be in the cards this summer, however, Helsley appears more likely to be moved than ever before. The only problem is that he’s currently in the midst of by far his weakest season since his breakout All-Star campaign in 2022. While he posted a sterling 1.83 ERA, 2.35 FIP, and 34.6% strikeout rate across his last three seasons, Helsley’s 2025 hasn’t been nearly that special. His 3.18 ERA in 34 innings of work is still 32% better than league average, but a 3.77 FIP is downright pedestrian thanks in large part to a massive drop in strikeout rate. He’s punching out just 24.8% of his opponents this year, all while walking 9.4% of batters faced. The 30-year-old still offers premium velocity and is clearly an above-average arm with plenty of closing experience, but he’s not quite the slam-dunk superstar he would’ve been this time last year.

Raisel Iglesias

Iglesias isn’t having an amazing season on the whole but is in a strong groove at the moment. He has a 5.12 ERA on the season but most of the damage came earlier in the year. From June 9th until July 18th, he tossed 13 2/3 scoreless innings with a 37.5% strikeout rate and 2.1% walk rate. His most recent outing was a four-run clunker, but that still leaves him with a 2.45 ERA over his past 14 2/3 innings. Though it’s not his best year, he has 235 saves and a 2.99 ERA in his decade-plus career, so he’ll certainly garner interest.

Kenley Jansen

In the midst of his 16th big league season, the 37-year-old Jansen has begun to show his age with declining peripherals (4.24 FIP, 4.43 xFIP) but has generally remained as effective as ever at closing out games when looking at pure results. His 3.28 ERA across 35 2/3 innings of work has been enough to allow him to convert 17 of his 18 save chances, and virtually all of the damage he’s allowed this year was part of a six-run, two-out blow-up back on May 2. He had made eight appearances without surrendering a run prior to that outing, and since then he’s posted a 2.33 ERA and 3.02 FIP across 27 innings of work. It’s hardly reasonable to ignore that meltdown earlier this season entirely, but given Jansen’s Hall of Fame caliber track record and strong performance in every other outing this season, it’s not hard to imagine contending clubs believing he’ll be more valuable than his season-long peripherals might otherwise suggest.

Steven Matz

The 34-year-old Matz stands out from the rest of the rental relief crowd as a hurler with plenty of starting experience who was used as a multi-inning reliever and spot starter as recently as earlier this season. His 3.29 ERA and 2.90 FIP across 52 innings of work this year are certainly impressive on paper, but a closer look at his numbers reveals some reason for pause. Since the start of May, Matz has been used exclusively in short relief and hasn’t exactly taken to the role change well with a 4.82 ERA and 3.73 FIP in 28 innings of work over his last 20 appearances. Perhaps an interested club would look at that improved peripheral and see potential, but it should be noted that Matz carries a massive platoon split this year; while lefties have been held to a .182/.222/.234 against him this year, righties have slashed a much more robust .290/.321/.435. That’s not exactly what you want from a late-inning reliever, but Matz could still provide unique value to clubs as a dominant hurler against lefties who could be stretched out for longer appearances as needed.

Other Options

The aforementioned five names are hardly the only options worth considering. Caleb Ferguson of the Pirates, Seranthony Dominguez of the Orioles, and Jakob Junis of the Guardians are among a number of set-up men in the midst of solid seasons, though none have numbers or track records quite as impressive as the group listed above. Kyle Finnegan of the Nationals has a long track record of success in the ninth inning but didn’t get much interest in free agency this winter and he now has a 4.62 ERA this year. Diamondbacks closer Shelby Miller would have a strong argument as one of the top options on this list if not for a forearm strain suffered early this month that could require surgery, though a return later this year has not yet been ruled out.

Who do MLBTR readers view as the best rental reliever available this summer? Should teams prioritize the strong track records of Helsley, Iglesias and Jansen, or the recent excellence of Coulombe? Or perhaps Matz’s flexibility to be used in multiple roles makes him most attractive of all? Have your say in the poll below: