In light of Rangers closer José Leclerc landing a big contract extension Wednesday, MLB.com looked at why the under-the-radar righty looks like one of the best relievers in the game. And back in January, Statcast analyst Mike Petriello profiled an even lesser-known reliever who should get more attention, Minnesota’s Taylor Rogers.
But even in an environment in which bullpens continue to take on a larger role, those two are far from the only exciting arms who remain relatively anonymous.
Expected weighted on-base average (xwOBA) is a Statcast-based metric that combines strikeouts, walks and quality of contact to show how a pitcher should have performed, independent of factors such as park effects and defense. There were 45 pitchers last season -- 34 of them relievers -- who faced at least 200 batters and posted an xwOBA below .270.
Leclerc and Rogers are part of that group, as are the five relievers below, each of whom deserve some more notice after intriguing 2018 performances.
José Alvarado, Rays
2018 stats: 64 IP, 2.39 ERA, 2.27 FIP, 30.4 percent K rate, .258 xwOBA
Note to know: Alvarado was one of five pitchers (minimum 50 innings) to post at least a 30 percent strikeout rate and a 50 percent ground-ball rate.
The left-hander, signed out of Venezuela in 2012, debuted with Tampa Bay five years later and took a big step forward last season, when he got a bit of work in the closer role (eight saves). Alvarado showed an ability to dominate right-handed batters (.495 OPS) as well as lefties (.582) last season, working mainly with a sinker that averaged upwards of 97 mph and generated both whiffs and grounders. He also throws a sharp curveball that, like the sinker, has one of the highest average velocities in MLB (85 mph).
Alvarado’s biggest issue was free passes (11 percent walk rate), but that improved down the stretch, when the southpaw got on quite a roll. Over 24 outings in August and September, he struck out an absurd 46.7 percent of batters he faced. While it might not be the Rays’ style to make the 23-year-old their full-time closer, he should see plenty of high-leverage opportunities.
Jace Fry, White Sox
2018 stats: 51.1 IP, 4.38 ERA, 2.67 FIP, 32.7 percent K rate, .269 xwOBA
Note to know: The 1.71-run gap between Fry’s ERA and FIP was the third largest for any pitcher who threw at least 50 innings.
A third-round pick out of Oregon State in the 2014 Draft, Fry got a taste of the big leagues late in ‘17 before spending most of last season with the Sox. The lefty did encounter some bumps in the road, allowing multiple earned runs in a game seven times, while recording no more than two outs in six of those. But there was a lot to like as well.
While Fry doesn’t throw particularly hard, he has a diverse repertoire, especially for a reliever. The 25-year-old leads with a sweeping cutter that caused opponents to miss on nearly half of their swings and yielded just a .169 batting average. Not surprisingly, Fry completely shut down left-handed batters (.143/.217/.190), and his overall strikeout rate ranked fifth among southpaw relievers with at least 50 innings.
Richard Rodríguez, Pirates
2018 stats: 69.1 IP, 2.47 ERA, 2.60 FIP, 31.5 percent K rate, .250 xwOBA
Note to know: No reliever in MLB recorded more strikeouts than Rodriguez on four-seam fastballs below 94 mph (52).
In the past year, Rodriguez made the sort of transformation you rarely see, as MLB.com Pirates beat writer Adam Berry recently detailed. A 28-year-old Minor League free agent who flopped in a brief debut with the Orioles in 2017, Rodriguez signed with the Pirates and blossomed, locking up a prominent relief role for the Bucs last season.
At first glance, it doesn’t seem like Rodriguez’s approach should work. The righty threw 75 percent four-seam fastballs and averaged roughly 93 mph -- below average for an MLB reliever in 2018. But between Rodriguez’s relatively high spin rate, his willingness to attack up in the zone, and what catcher Francisco Cervelli described as “weird” mechanics, the pitch yielded only a .260 slugging percentage.
Will Smith, Giants
2018 stats: 53 IP, 2.55 ERA, 2.07 FIP, 33.8 percent K rate, .222 xwOBA
Note to know: Smith’s .244 xwOBA allowed since Statcast debuted in 2015 ranks seventh in MLB (minimum 500 batters faced), behind Kenley Jansen, Andrew Miller, Sean Doolittle, Aroldis Chapman, Edwin Diaz and Zack Britton.
Smith is probably the most widely known pitcher on this list, having appeared in nearly 300 games over six MLB seasons for the Royals, Brewers and Giants. He still doesn’t draw enough attention, however, as a pitcher with little closing experience who missed all of 2017 due to Tommy John surgery and toiled for an 89-loss Giants club in ‘18.
But San Francisco has a fascinating bullpen heading into this season, with righty Reyes Moronta another hidden gem to watch. Smith could be in the mix to close games, and/or become trade bait in his walk year if the club falls out of the race again. The southpaw struck out 30 of the 72 left-handed batters he faced in 2018 and is plenty tough on righties, who went 5-for-52 (.096) against his slider.
Kirby Yates, Padres
2018 stats: 63 IP, 2.14 ERA, 2.54 FIP, 36 percent K rate, .256 xwOBA
Note to know: The only NL reliever with a larger gap between his strikeout and walk rates than Yates (29.2 percent) was the Brewers’ Josh Hader.
It’s been a long road for Yates, a righty who turns 32 this month. The Hawaii native was a 26th-round Draft pick who has spent at least parts of the past five seasons in the Majors but was designated for assignment four times by three different teams before finding a home with the Padres. He’s now the team’s closer, a role he inherited after Brad Hand was traded to the Indians last summer.
In San Diego, Yates was encouraged to lean on a splitter he had recently developed, an approach that has made a world of difference. Working off a 94-mph four-seamer, the 87-mph split falls off the table and makes life difficult for hitters. Over the past two seasons, the pitch has generated a 46 percent whiff rate, with opponents batting .126 with 83 strikeouts in 143 at-bats.
Andrew Simon is a research analyst for MLB.com. Follow him on Twitter @AndrewSimonMLB.