2026 NL Reliever of the Year Race Breakdown: Mason Miller vs. Edwin Diaz

The MLB Reliever of the Year race is shaping up to be one of the most unpredictable—and entertaining—markets of the 2026 season.

Bullpens are notoriously fluid, and this market tends to move with every shift in role, every blown save, and every new opportunity that pops up over a 162-game grind. It’s not just about racking up saves anymore, either. Voters have started to lean into the full picture—strikeout rates, high-leverage usage, and how dominant a reliever truly is when the game is on the line.

National League Reliever of the Year Probabilities

2026 NL Reliever of the Year Probabilties — Kalshi

Right now, the National League is home to the two biggest names in the race. According to Kalshi, Mason Miller has surged into the lead at 37%, with Edwin Díaz right behind at 24%. Jhoan Durán isn’t far off either, sitting at 17% and firmly in the mix.

With three electric arms at the top and plenty of season left, this market is far from settled—so let’s break down the contenders and where the value might be.

Mason Miller, San Diego Padres (37%)

Miller has a strong case as the most overpowering closer in baseball, but his 2025 season wasn’t without turbulence. A brutal six-game stretch in May (10 runs, 17 baserunners, two home runs, and 12 strikeouts over 5.2 innings) led to two losses and two blown saves in three chances, and a midseason trade to the San Diego Padres temporarily pushed him into a setup role.

Outside of that, Miller was electric. He opened the year with a 12-game run (1.50 ERA, 0.667 WHIP, 23 strikeouts over 12.0 innings) while converting all 10 save chances. After the May hiccup, he bounced back by converting 10 of his next 12 opportunities, posting a 1.29 ERA, 0.714 WHIP, and 67 strikeouts across 42.0 innings. He closed the season on a ridiculous note—21.1 straight scoreless innings with 42 strikeouts.

The stuff is as loud as it gets. His fastball averaged 101.2 mph and made up 51.7% of his arsenal, with hitters managing just a .162 average and 52 strikeouts against it. His slider was even more untouchable (.104 BAA, 59 strikeouts), while his changeup was more of a show-me pitch (22 total throws, one hit, one strikeout).

Command remains the one area holding him back. Miller threw first-pitch strikes just 57.4% of the time, contributing to a 4.1 walk rate. If that number creeps closer to 65%, you’re looking at a different level entirely. Even with the inconsistency, he posted a career-best strikeout rate (15.2 overall, 17.4 with San Diego), and right-handed hitters had no answers—65 strikeouts in 132 plate appearances.

Mason Miller Early 2026 Stats

He’s carried that dominance into 2026. Across 6.1 innings in six appearances, Miller hasn’t allowed a run, owns a 0.32 WHIP, and has struck out 16 batters with just one walk. He’s already converted four saves and given up only one hit. If this pace holds, the award race could get lopsided in a hurry.

Edwin Diaz, Los Angeles Dodgers (24%)

2026 NL Reliever of the Year Candidate: Edwin Diaz, Los Angeles Dodger — Los Angeles Dodgers pitcher Edwin Diaz (3) delivers to the plate as he earns a save in the ninth inning against the Arizona Diamondbacks at Dodger Stadium. | Jayne Kamin-Oncea-Imagn Images

Díaz, now with the Los Angeles Dodgers, is right there in the mix at 24%. Los Angeles brought him in on a three-year, $69 million deal after already investing $72 million in Tanner Scott the year prior, signaling just how serious they are about locking down the late innings.

Díaz is coming off his fourth career season with a sub-2.00 ERA. In three of those years, he paired elite strikeout production (13.3–14.5 K/9 range) with improved command (2.1, 2.6, and 2.8 BB/9). The New York Mets had 40 saves last season, and Díaz converted 70% of them, though his first-pitch strike rate dipped to 55.2%—a notable drop from his 71.1% peak in 2022 (61.9% in 2024).

There were a few bumps. He got tagged in back-to-back outings in April (five runs, seven baserunners, one home run over 1.2 innings) and had a rough August (four runs, 11 baserunners, two home runs over 9.0 innings). But in between, he showed his usual dominance, including a 17-game stretch from June into July where he didn’t allow a run (13 baserunners, 25 strikeouts over 17.1 innings).

The arsenal is still elite. His fastball averaged 97.3 mph, and he leaned heavily on a two-pitch mix—four-seamer (.128 BAA) and slider (.172 BAA, 59 strikeouts). He was equally tough on both sides of the plate (.171 BAA vs. righties, .158 vs. lefties).

Edwin Diaz Early 2026 Stats

Early in 2026, Díaz has allowed one run over 5.0 innings (1.80 ERA), with eight strikeouts, three walks, and just two hits allowed (1.00 WHIP). He’s already picked up four saves, and in a Dodgers bullpen that should generate plenty of opportunities, he has a real shot to lead the league in that category.

Jhoan Durán, Philadelphia Phillies (17%)

2026 National League Reliever of the Year Candidate: Jhoan Duran, Philadelphia Phillies — Philadelphia Phillies pitcher Jhoan Duran (59) reacts after a victory against the Texas Rangers at Citizens Bank Park. | Bill Streicher-Imagn Images

Jhoan Durán checks in at 17% and continues to trend upward after joining the Philadelphia Phillies at last year’s trade deadline in a deal that sent Eduardo Tait and Mick Abel to the Twins.

2025 was a breakout in both usage and performance. Durán made 72 appearances, set career highs in wins (7), saves (32), and innings (70), and showed a major leap in command—just one walk over 20.2 innings down the stretch, paired with 27 strikeouts. He also posted a career-best first-pitch strike rate of 64.2%.

There are still a few quirks in the profile. Right-handed hitters had some success (.278 average), though they managed just six extra-base hits over 126 at-bats. He’s also vulnerable to the running game (13-for-14 on stolen base attempts allowed) and gave up a career-high 41.6% hard-hit rate, even while maintaining an elite 65.0% groundball rate.

The raw stuff, though, is undeniable. His fastball averaged 100.5 mph, just a tick behind Miller. He leaned most heavily on his sinker (40.0% usage, .233 BAA), while also mixing in a four-seamer (.209 BAA), curveball (.185 BAA), and occasional slider (.167 BAA). Even when hitters made contact, it was often limited to singles—16 of them allowed to righties over 63 at-bats.

Jhoan Duran Early 2026 Stats

He’s picked up right where he left off last season. Through 5.2 innings in six appearances in 2026, Durán has converted four saves, struck out seven, and hasn’t issued a single walk. The 1.59 ERA and 0.88 WHIP may not hold all year, but the early returns in Philadelphia have been outstanding.

In a crowded field, Durán’s combination of velocity, improving command, and role security keeps him firmly in the hunt.

Accuracy note: Market data referenced in this article reflects information as of Friday, April 10, 2026. Prediction market prices are live and shift continuously. Always verify current information directly at Kalshi.com and Polymarket.com before trading.

Trading is risky, always trade responsibly. If your activity is becoming a problem, support is available by calling 1-800-522-4700.