If the 2018 season will be remembered for anything, I think it’ll be remembered as the year of the bullpen. While Edwin Díaz and Blake Treinen thrived in traditional roles, Josh Hader and a cadre of Rays relievers broke with tradition and forged new paradigms in bullpen usage. What the Rays did was completely unconventional, but Josh Hader was following in the footsteps of other relief firemen like Andrew Miller. But even Miller was used as a more traditional setup man more often than not. What the Brewers created in their bullpen this year was something even more extreme. And I think it’s worth exploring for the Mariners.
The Mariners relief corps was actually one of the strengths of the team in 2018. Led by Díaz’s historic season in the ninth inning, a solid group of setup men capably set the stage for him. As a group, Mariners relievers ended up ranked fourth in the American League by league adjusted FIP- and compiled 164 Shutdowns, FanGraph’s win-probability-powered relief metric. Álex Colomé, Juan Nicasio, James Pazos, and Nick Vincent were each significant contributors to a solid back end of the bullpen. And all five of those relievers, including Díaz, are under team control in 2019.
Despite the majority of this team strength carrying over into next year, it would be worthwhile to look at how the Brewers deployed their bullpen in 2018 to see if there’s anything to be learned. The relief fireman isn’t unique to the Brewers. Teams were using their best relievers outside of the ninth inning well before this year. What was unique about Hader was how early Craig Counsell was willing to use him. In Game 7 of the National League Championship Series, Hader was called on in the third inning after Jhoulys Chacin couldn’t keep the Dodgers off the board. In the regular season, he was inserted into a game as early as the fourth inning and most commonly appeared in the sixth or the seventh. He also often pitched more than a single inning—about two-thirds of his appearances were multi-inning appearances.
Managers are often hesitant to deploy their best reliever in these mid-game, high-leverage situations because they’re fearful another high-leverage situation will develop later in the game. They’re saving their best bullet for the absolute best moment. Of course, the middle relievers used in these mid-game, high-leverage situations often blow it, robbing the manager the opportunity to use his best reliever. Buck Showalter’s refusal to use Zach Britton in the 2016 American League Wild Card game is perhaps the most famous example of this tendency.
If Josh Hader was the only good reliever in Milwaukee’s bullpen, you could understand why a manger would be hesitant to use him too early. Luckily for the Brewers, they had no less than three relievers with closing experience in their bullpen. Corey Knebel, Jeremy Jeffress, and Joakim Soria gave Counsell ample options to use after Hader reached his limit in the sixth or seventh. He could confidently deploy his best reliever early knowing he had strong options to use later.
The Mariners are flush with a number of strong options that could be used flexibly like the Brewers. Unfortunately, Scott Servais seems to be devoted to rigid bullpen roles. Díaz was used in the eighth inning just three times in 2018, each time earning just a single additional out. After joining the Mariners in May, Colomé was used outside the eighth inning just eight times—17% of his appearances—and just three of those appearances came in the seventh. Before Colomé joined the team, Nicasio was used in the eighth inning in 80% of his appearances. That kind of commitment to fixed bullpen roles isn’t surprising—it’s been the modus operandi for major league teams for the past few decades. But could it have cost the Mariners a few wins during the regular season? What could a flexible Brewers-style bullpen look like?
Let’s put our hypothetical-situation-slash-time-travel caps on and go back to August 31, 2018. The Mariners are playing the second game of a four-game series in Oakland. It’s arguably the most important series of the year and they had cruised to an easy 7-1 win in the first game. The second game hasn’t gone as well. The A’s scored five runs in the first but the Mariners had rallied to tie the game in the top of the fourth. Mike Leake had managed to stem the tide of runs but had allowed at least one baserunner in each inning since the first. Heading into the bottom of the fifth, Leake has thrown 84 pitches to that point. I can understand leaving Leake in to try and finish the fifth, but after allowing the leadoff man to reach second, action needs to be taken to maintain the tie game. Instead, Servais allows Leake to face another three (!) batters—two of them reach on line drive singles and the other scores the deciding run via a line drive sacrifice fly.
What if Díaz or Colomé had been inserted into the game at that point to keep the game tied? The leverage index at the beginning of the bottom of the fifth was 1.17, a little higher than average. After the first baserunner reached second, it jumped up to 1.55. After the second hit of the inning, it was 1.79. Wouldn’t you want your best reliever pitching in the most critical situation in an extremely important game? And even if Díaz or Colomé had been used in the fifth, the other one would have been available for any potential ninth inning save situation.
The obvious mirror to the Brewers bullpen would be to use Díaz as a relief fireman. But even if Servais wants to keep some semblance of traditional bullpen roles intact, wouldn’t some flexibility be better than none at all? If Díaz is going to be stuck in the ninth inning, why does Colomé need to be glued to the eighth inning? For all his warts, Juan Nicasio ran the second best strikeout-to-walk ratio among relievers with at least 40 innings pitched. If Colomé is used in a fireman-style role, Nicasio can likely hold down the eighth inning, assuming his run prevention bounces back in 2019. James Pazos, Nick Vincent, and even Shawn Armstrong provide even more options for Servais to use after potentially calling on Colomé during the middle innings of a game.
A strong bullpen is critically important in this era of baseball. With good starting pitching growing more and more scarce, relievers are being called on to carry more and more of the burden. But simply lining up your best relievers from the ninth inning and working backwards just isn’t enough. The 2018 Brewers proved that a fluid and flexible bullpen can cover a weak starting rotation and provide strong relief options whenever a crisis arises. The Mariners have the pieces in place in 2019 to build a bullpen similar to the 2018 Brewers. Whether it’s Díaz, Colomé, or Nicasio in the fireman role, maximizing their bullpen usage will be critically important if they’re serious about making another run at contention next year.