2026 Fantasy Baseball Sleepers: Relief Pitchers

Welcome back to RotoWire's new feature listing our favorite sleepers by position, with three sleepers and one deep sleeper at every position on the diamond. For the purposes of this series, here's how we're defining "sleeper" and "deep sleeper":

• Sleeper: a player being drafted between picks 150 and 350 who could significantly outperform his draft price
• Deep Sleeper: a player being drafted after pick 350 who could significantly outperform his draft price

So far, we've covered catchers, first basemen, second basemen, third basemen, shortstops, outfielders and both AL and NL starting pitchers. We conclude the series by looking at relief pitchers for your 2026 fantasy baseball drafts.

Note: The average draft position in this article is taken from all Draft Champions leagues that have drafted over the past month.

Best 2026 Relief Pitcher Sleepers

Dennis Santana (ADP 167.5, RP 19)

Evaluating closers is just as much about circumstances and environment as it is individual player skills, and Santana's circumstances have moved in both positive and negative directions this offseason. The Pirates did a decent amount - particularly for their standards - to improve their lineup and should at least contend for a playoff spot. That will do two things for Santana: improve the team's win potential, which would increase his save opportunities. And if that turns out to be the case, Santana is less likely to be traded at the deadline and lose the closer role.

As for the negative, the Pirates also added two potential high-leverage bullpen arms in Gregory Soto and Mason Montgomery. That adds some added competition for saves, particularly if a lefty-heavy portion of opponents' lineups are due up in the ninth inning. However, Soto has settled in as a setup man over recent seasons with high WHIPs the last two (1.57 and 1.43, respectively). Montgomery boasts nasty stuff, yet that hasn't translated to consistent big-league results.

Santana's own skillset also isn't that of a prototypical closer with a career strikeout rate of only 22.1 percent and 22.2 last year. Allowing that level of consistent contact will introduce variance that isn't present for other closers. The one stat that is particularly reassuring from 2025 is Santana's work during save situations as he maintained a 36:9 K:BB with a 1.65 ERA and 0.74 WHIP across 32 appearances and 32.2 innings. Those results may not be sustainable, but it's bound to gain some trust with manager Don Kelly to give him breathing room as the closer to start the season. 

Seranthony Dominguez (ADP 230, RP 23)

In some ways, the case for Dominguez is similar to that of Santana. The White Sox have taken at least a step forward by improving their depth with the additions of Munetaka Murakami and Austin Hays. They remain very unlikely to challenge for the postseason, though should surpass last 2025's win total of 60 in which they only recorded 27 saves.

Even if the team only generates 30 total saves, Dominguez should account most of them. Manager Will Venable didn't waste any time naming him his closer, so there's no guesswork as to who will be called upon in the ninth inning.

There are still reasons for concern. Dominguez has shown significant skills flaws the last few campaigns with 1.26 and 1.84 HR/9 in 2023 and 2024. He also surrendered a 13.8 percent walk rate last year while reducing his HR/9 to 0.72. Pitching director Brian Bannister discussed ongoing concerns about Dominguez's skills and pitch mix, suggesting a splitter he added in 2025 will reduce Dominguez's susceptibility to left-handed hitters. He may not be the perfect closer, yet everything points to the organization having a significant amount of faith in him. For draft season, that's good enough as Dominguez's ADP is low enough that it will be easy to move on if he's dealt at the deadline or otherwise falls out of favor as the closer.

Bryan Abreu (ADP 268, RP 25)

For those on the hunt strictly for saves, Abreu is a boom-or-bust option. Josh Hader has dealt with some form of arm injury since the second half of last season, first sidelined by a shoulder strain before being slowed this spring by a bicep issue. Hader will clearly be the closer if he proves to be healthy, but that's reasonable to question given this recent news.  

Abreu would be more than capable of filling in for Hader as long as necessary. He's turned in elite ratios for four consecutive seasons while also striking out at least 31 percent of the batters he faced during each campaign. While Abreu has only registered 16 career saves, he's also picked up 102 holds and well-versed in high-leverage usage.

While these articles are geared toward roto leagues and this one is heavily influenced by the potential to earn saves, it's worth mentioning Abreu's potential utility in points formats. In addition to his elite skills, he's logged at least 71 innings during each of the last three seasons while reaching at least 100 strikeouts from every year. Streaming that type of volume is valuable late in matchups. For leagues that reward holds, Abreu becomes an even more desirable option.

Deep Sleeper

JoJo Romero (ADP 484, RP 41)

The exact allocation of Cardinals' saves outlook is ambiguous, though Romero and Riley O'Brien figure to be the top two candidates. Unfortunately, there's very little to separate the duo as they posted nearly identical skills profiles during 2025. And while Romero immediately took the closer role following the departure of Ryan Helsley after the Trade Deadline, O'Brien finished by accounting for four of the final five save opportunities.

For now, there are a few factors that push me toward Romero. The first is ADP. O'Brien is RP 27 off the board, 202 overall picks higher than Romero. In an uncertain situation, Romero comes at a significant discount. The second is a small point, but O'Brien is nursing a calf injury that could slow his progress this spring. While he's expected to be ready for Opening Day, missed time could shift the confidence of manager Oli Marmol toward Romero.

Even if Romero begins the campaign as the Cardinals' closer, he's at a high risk of losing the job either due to performance or because he'll be traded. But this late in the draft, banking any number of saves is valuable and Romero is one of the few relievers at this ADP who offers potential to immediately contribute. 

Who is your top relief pitcher sleeper for 2026? Let us know in the comments below.