The jury is out on the Red Sox bullpen. There has been plenty of consternation about this group for the last couple of years, some of which has been warranted and some has been a bit overblown. They weren’t really a plus last year, and early in the year they were a minus, but as the season went on their reputation was worse than their actual performance. I’ve already made the argument that I feel weirdly good about the unit, and as a staff we’ve largely felt that they don’t necessarily need a big-time addition, though it certainly wouldn’t hurt.
To this point in the offseason, though, Chaim Bloom and company haven’t really done anything of significance to add to the group, which is the same that could be said about Dave Dombrowski and company in the previous 18 months or so. That is not, however, the same as saying they haven’t done anything. While there haven’t been a lot of exciting moves, Bloom has been busy reshaping the bottom of the 40-man roster with a bunch of different arms with minor-league options. Since the offseason began, the Red Sox have added Josh Osich, Chris Mazza, Austin Brice, Jeffrey Springs and Matt Hall, plus Kyle Hart and Yoan Aybar were added to the 40-man to protect them from the Rule 5 Draft.
You’ll be forgiven if you’re not excited about these additions because, well, they aren’t very exciting. You’ll also be forgiven if you’re not excited about the bullpen as a whole because, well, even if they may have been underrated in the second half and even if I think they’re pretty much okay, they don’t exactly jump off the page. One thing that does jump off the page, though, is that this bullpen freaking loves curveballs.
It should be made clear that this is neither a new strategy being employed by Bloom nor is it anything new for the Red Sox. Last season their bullpen led baseball, per Fangraphs, by throwing a curveball 19.5 percent of the time, with second place coming in at 15.9 percent. Similarly, they led baseball in 2018 with a rate of 20.3 percent while second place came in at just 13.4 percent. On the flip side, the Rays were towards the bottom of the league last season with Bloom. Looking at how things stack up right now, they should be right at the top of that leaderboard again in 2020.
The common factor in the bullpen in each of the last two seasons has, of course, been Matt Barnes. The righty has a big fastball that can light up the gun in the high-90s, but it’s his curveball that he leans on and he threw it more than half the time last year. They’ve also had closer-heavy closers in the last two seasons, with Craig Kimbrel taking that mantle in 2018 and Brandon Workman being the guy last year. Workman is, of course, back for 2020, and like Barnes he threw his curve more than half of the time. Colten Brewer certainly is not as important of a piece as those two — he may not even make the Opening Day roster — but he is another curveball-heavy pitcher who uses that pitch as the focal point of his arsenal.
Not all of Bloom’s fringe-additions have been curveball aficionados, but two of them figure to fit this pattern. Austin Brice came over from the Marlins a year after remaking his arsenal (apparently by accident, which I find hard to believe but what do I know) in a way that is now featuring his curveball more than any other pitch. Matt Hall, meanwhile, hasn’t quite emphasized his curveball like the other names mentioned here but it has been his most effective pitch and it’s not hard to envision him attempting a similar strategy.
So, with all of those guys, the Red Sox have the foundation of a curve-heavy bullpen. In fact, looking at Statcast’s leaderboard, they have four of the top eight pitchers (minimum 250 pitches) in terms of rate of curveball usage. Hall is the only one of the five mentioned above in that group, but again the numbers show he may benefit from an increased usage rate. It’s also worth noting he was in the top five percent of pitchers in curveball spin rate, perhaps another sign he could benefit from greater focus on the offering.
So, what does this all mean? I don’t know! Does it mean that the Red Sox think they have found some sort of market inefficiency? I’m not sure you can say that with any sort of certainly, particularly since they figure to get major innings from Josh Taylor, Darwinzon Hernandez and Marcus Walden, none of whom throw curveballs. On the other hand, it’s possible they saw the success Workman had with this strategy — and in particular what it allowed him to do with his fastball, which in isolation is not particularly special — and think they can try to turn a couple of cheap additions into breakouts in 2020. It is certainly easier said than done to do what Workman did last year, but it’s also undeniable the success this methodology had for him. At the very least, I am certain that if you enjoy watching curveballs, you’ll get a kick out of watching Boston’s bullpen in 2020.