In an era when relievers throwing in the upper 90s is more requirement than luxury, ace relievers seem to rise and fall with incredible frequency.
Two years ago, the best seven relievers by fWAR were Kenley Jansen, Craig Kimbrel, Roberto Osuna, Corey Knebel, Pat Neshek, Chad Green and Andrew Miller. Just a season and a quarter later, Jansen and Osuna have been good but not great, Kimbrel can't find a job, Knebel is out with an injury and Neshek, Green and Miller all have been below replacement level.
While that churn is disappointing, a new crop of relievers has stepped forward to fill the void. The relievers listed below are breaking out in a big way.
Heading into last season, Brad Hand was the relief ace in San Diego. Yates pitched decently in 2017, but too many homers made him closer to average as a reliever. Last year, Yates began to more heavily mix in a split-fingered fastball and did a very good job taking over after Hand's departure. This season, he's increased the use of the splitter to more than 40% of his pitches and he's been a strikeout machine even with a low-90s fastball. Yates has struck out more than 45% of the batters he's faced as hitters are unable to guess whether they will receive a splitter out of the zone or a fastball for a strike.
Remarkably, the righty has given up no home runs this year on his way to a 0.82 FIP, 1.08 ERA and 1.7 fWAR that leads all relievers. He might give up a few home runs as the season wears on, but he should continue to be one of the best in the game just two years after the Padres found him on waivers after he spent time with Yankees, Rays and Angels.
Ty Buttrey, Los Angeles Angels
While the Angels' loss was the Padres' gain with Yates, it seems Los Angeles has found its own gem in Ty Buttrey. The tall right-hander came over to the Angels last season from Boston in the Ian Kinsler deal and finished the season strong with 20 strikeouts in 16⅓ innings.
Buttrey uses a high-90s fastball and low-80s slider to miss bats, but also mixes in a changeup to keep lefties on their toes. He's got 35 strikeouts against just seven walks and has allowed just four runs in 28 appearances this season. Buttrey's three-pitch repertoire ensures that hitters can't get too comfortable, not that they would anyway facing a fastball that averages 97 mph.
Ken Giles had his relief breakout back in 2014 with the Phillies, but after several dominant seasons, a disappointing 2017 postseason performance was followed by an uneven 2018 campaign that saw him get traded to the Blue Jays midseason. After that lull in performance, Giles is back and his traditional fastball-slider combo has led to 34 strikeouts against just five walks in 21⅔ innings.
Giles was perhaps too eager to attack hitters last year, throwing his fastball more often with a greater number of pitches in the strike zone. This season, Giles is close to 50/50 in usage between his fastball and slider and is trying to force hitters to chase balls out of the zone more often. So far it is working as hitters have swung and missed on one out of every five pitches Giles has thrown, including 27% of his sliders. It seems the Giles that went away at the end of 2017 is back and dominating again.
Last year, it was the unknown Ryan Brasier who came in and helped stabilize the Boston bullpen. This year, that role belongs Marcus Walden, a 30-year-old righty who pitched in all of eight games before this season after being drafted by the Blue Jays a dozen years ago.
The Red Sox signed Walden to a minor league deal before the 2017 season and let him start in Triple-A for a time before converting him back to a reliever. Walden started emulating Craig Kimbrel's slider, and now the pitch is his primary offering; 21 of his 34 strikeouts have come on the pitch. With a sinker and a cutter also in his arsenal, Walden mixes in a lot of ground balls with his strikeouts, and that's a good combination for avoiding homers.
Ryan Pressley was a good reliever with the Twins last year, striking out a third of the batters he faced with a 3.40 ERA and 2.95 FIP in 47⅔ innings. After a trade to the Astros, Pressly took his game to another level by throwing more curveballs and fewer fastballs. More curves meant more strikeouts and fewer fastballs meant a drop in homers.
So far this season, Pressly is showing that the late-season changes have stuck. Pressly has walked just two batters and given up one homer, the only run he has allowed all season. The curve, along with a strong slider, have caused a near-60% ground ball rate on the season. He can't possibly keep up a 0.36 ERA the rest of the way, but his emergence as a late-inning shutdown reliever is here to stay.
What happens when you add a few more ticks to your fastball, then throw your slider half the time? You go from a middle-of-the-road reliever to a solid closer. Luke Jackson's fastball averaged around 94 mph over the past few seasons, but he's shot up to 96 mph this year. Increasing the usage of the slider has left hitters frozen on fastballs in the strike zone as they have swung at just 61% of fastballs in the zone while chasing nearly half the sliders out of it.
With the curve a third offering, Jackson has struck out nearly one third of the batters he's faced while issuing just five unintentional walks. Only Zack Britton and Chad Bettis have a higher ground ball rate than Jackson's 72% mark this season. He might not be the closer all season if the Braves make other additions or get players back from injury, but he should help out in any role with the club.
In 2017, Amir Garrett got a taste of the majors in the Reds' rotation and gave up 23 homers in just 70⅔ innings. Last season, the lefty was moved to the bullpen and had a pretty average season. But a year after getting acclimated to the 'pen, Garrett is thriving.
He's another pitcher who has moved away from the fastball and increased the use of his slider to great affect. Garrett has thrown the slider nearly 200 times this season and given up just three hits on it. He has an absurd 31% whiff rate on the offering with 30 of his 36 strikeouts coming off the slider. He's also thrown a two-seam fastball more often, which has helped keep the ball on the ground. In Cincinnati, as teams get more homer-happy, the sinker-slider combo will continue to serve Garrett well.
John Gant, St. Louis Cardinals
A year ago, John Gant was a nondescript swingman bouncing between Triple-A and the majors, the bullpen and the rotation. He didn't pitch poorly, but his 93 mph fastball wasn't blowing hitters away. After losing a spring training battle with Dakota Hudson for the final spot in the St. Louis rotation, Gant was out of options so he moved to the bullpen.
Needing to go only an inning at a time, his fastball jumped up to 96 mph on average and as hard as 99 mph on occasion. That extra velocity is exactly what Gant needed to go from so-so starter to really good reliever. As long as the Cardinals don't need Gant back in the rotation, he'll be a key piece for the bullpen moving forward.