Who should pitch the important innings out of the Red Sox bullpen?

As the new manager of the Boston Red Sox, Ron Roenicke will make a lot of decisions this season. These won’t be decisions new to him, as he spent parts of five seasons as the Milwaukee Brewers‘s manager, and it won’t be with a new team since he was Boston’s bench coach the last two seasons.

Even with all that familiarity with the role and the team, some managerial decisions are difficult. Using relievers in the right spots and delineating the right roles to those pitchers is among the most difficult as well as the most scrutinized.

Roenicke is inheriting pretty much the same bullpen that the Red Sox ran with last season. The Red Sox made several small moves, such as trading for Austin Brice, Matt Hall and Jeffrey Springs, and claiming Josh Osich and Phillips Valdez off of waivers, but in general, they kept things the same. For a group that was near the middle of MLB in performance and powered by unexpected seasons from the likes of Brandon Workman and Marcus Walden, it might seem odd that the bullpen wasn’t addressed. However, we’re not here today to judge the front office so much as evaluate how the relievers on hand did in the most important times last season.

The tide is turning against the thinking that the ninth inning is always saved for your best and most “clutch” pitchers. So instead of just looking at who pitched the best in the final inning, we’ll be examining how some of the Red Sox relievers expected to contribute the most this season fared in high leverage situations last season. This in turn may give us a portion of the optimal strategy for how Roenicke can use the bullpen.

As a group, Red Sox relievers had a 7.33 ERA and gave up an opponent wOBA of .331 in what FanGraphs defines as high leverage situations. The Sox ranked 21st in the majors in both of those categories, so we’re already starting from a place where they had issues. Only eight Red Sox pitchers logged at least five high leverage innings last season and only four (Workman, Walden, Matt Barnes and Ryan Brasier) finished with more than 10. So, obviously we’re not dealing with the biggest samples here.

At first glance, perhaps unsurprisingly, the pitcher who handled these spots the best was Workman. He had a 4.56 ERA and faced 109 batters in high leverage situations, which were both the best marks among Red Sox pitchers with at least 10 high leverage innings pitched. That’s a pretty great number since the league average ERA was 7.00. However, ERA isn’t necessarily the the best metric to determine who gets the ball in every high leverage situation. Workman had a 21.1 percent walk rate in high leverage situations last season, which was the most among the four Red Sox pitchers with at least 10 high leverage innings.

A deeper dive on the peripherals indicates that Walden and Barnes may have been a bit more successful. Barnes had the highest strikeout rate (37.5 percent) and a FIP slightly lower than Workman when leverage was high (3.34 vs. 3.37), while Walden had both of them beat at a mark of 2.66. There’s even an argument to be made for Brasier and his walk rate of 7.8 percent. However, Brasier has a 9.58 ERA in high leverage situations during his career and most of his peripheral numbers from 2019 pale in comparison to those of Barnes, Walden and Workman.

If we add more ingredients to this high leverage pot, we’ll find that Barnes actually stands out as the better option. In 12 high leverage innings in which he pitched with runners in scoring position, Barnes had a 1.63 FIP and 40.4 percent strikeout rate last season. That second number is perhaps more indicative of success considering inherited runners who scored wouldn’t be blamed on Barnes. The fact that Barnes left 47.6 percent of runners on base in such situations and Walden and Workman both settled below 30 percent is another positive mark for Barnes’ resume. Barnes even limited his home run problems, as he allowed 1.2 per nine innings in high leverage situations overall, but 0.5 per nine innings with runners on base and zero per nine innings when runners were in scoring position.

Walden also has a claim to the best high leverage pitcher crown because he avoided free passes when the pressure mounted and the bases weren’t empty. He had a walk rate of 7.3 percent compared with marks of 14.3 percent for Barnes and 20.2 percent for Workman in those spots. However, with a left on base rate of 16.7 percent, its tougher to make the argument for Walden, especially considering he has only pitched 13 high leverage innings in his career. For comparison’s sake, Barnes has thrown 66 ¹⁄₃ high leverage innings and Workman has thrown 45 ²⁄₃.

While Barnes, Walden, Workman and Brasier had the most experience pitching when the stakes were the highest with Boston in 2019, they are not the only pitchers who could be used in such situations. Josh Taylor had a 2.86 FIP and 4.76 ERA in high leverage innings last season, although he only had 5 ²⁄₃ of them. Colton Brewer also showed some promise in his small sample of high leverage innings (5 ¹⁄₃) with an 8 percent walk rate and 72.7 percent left on base rate, although he rarely got strikeouts and his xFIP was the highest among those who logged at least five high leverage innings for the Red Sox (6.20). Heath Hembree only had five such innings himself, but his 1.80 ERA and 2.01 FIP in that time in addition to his track record (36 career high leverage innings) make him someone who should get a look as well. Then there’s Darwinzon Hernandez. Unfortunately, it’s tough to evaluate his work in high leverage moments since he had just 1 ²⁄₃ such innings as a reliever, but a 16.20 ERA doesn’t inspire confidence.

There are obviously other relievers on the roster, but based on FanGraphs’ projections, the Red Sox will use Barnes and Workman the most out of the bullpen this season, with Taylor, Hembree, Hernandez, and Walden getting the most play from there. Workman is the nominal closer and his solid ERA in high leverage spots backs that up. However, it is possible Barnes, Taylor, Hembree and even Walden could be used effectively in such a role or in important moments throughout the game. Now we’re left to wonder if that kind of flexibility makes Roenicke’s job more or less difficult.