The Bullpen and Run Prevention

Last postseason, the Astros stormed their way to a second World Series title primarily due to their incredible run prevention. And it wasn’t a surprise when it happened as run prevention was kind of Houston’s bread-and-butter in 2022 as the club finished second-lowest ERA and allowed the second-fewest runs in baseball. When it was all said and done, the entire pitching staff posted an incredible 2.29 ERA (32 earned runs allowed) in 126 postseason innings, accumulating 160 strikeouts compared to only 43 walks. While batting average has its well-known limitations in terms of analysis, limiting opposing hitters to a collective .172 batting average across three rounds fraught with high-leverage moments will always remain impressive.

But for as efficient as the rotation was, the bullpen was even better, limiting opposing lineups to a .126 batting average and posting a minuscule 0.83 ERA. In relief, the Astros allowed only five earned runs across 54 ¹⁄₃ innings, an essential aspect of last year’s success. While the bulk of the roster reflected Jeff Luhnow’s influence, the bullpen was noticeably fortified by James Click when he acquired the likes of Héctor Neris, Ryne Stanek, Rafael Montero, and Phil Maton. While Maton didn’t pitch in the postseason last year due to an injury of creation, and Stanek was relegated to more of a reserve role, we watched Neris and Montero throw a combined 15 ¹⁄₃ innings, allowing only three earned runs. Along with Ryan Pressly and Bryan Abreu, Dusty Baker had at least four quality arms out of his bullpen to use aggressively.

That same blueprint exists today, more or less. While Montero’s stock has noticeably fallen on the heels of an ill-advised three-year, $33 million contract, Neris, Abreu, and Pressly have continued as the club’s top three relievers. Despite Maton’s impressive start to his 2023 campaign — 1.77 ERA in his first 40 ²⁄₃ innings — the results have deteriorated as his workload compounded. These struggles are one reason why Dana Brown felt it necessary to reacquire Kendall Graveman from the White Sox for Korey Lee at the trade deadline. In any case, Baker has six relievers who are either currently successful or have some history of performing well in the postseason, with Neris, Abreu, and Pressly viewed as the best that the Astros have in relief.

The trick for Baker is determining when to deploy his best arms, which has been an issue at times, especially with runners in scoring position outside of the later innings. Earlier in the season it was Maton who usually drew that assignment, with Montero sometimes receiving the call since his summer mini-resurgence. To be fair, the former has rebounded a bit with a 0.77 ERA and 94.3% LOB% in September, but those midsummer struggles still stand out. If there is a weak spot in this bullpen, it lies within those pesky middle innings as Baker prefers to keep his best arms available typically for the seventh through ninth innings. Not a fan of that strategy under certain circumstances, but we all know how Baker manages at this point. For example, there were a handful of instances this season when one could argue that Neris or Abreu would’ve been the more appropriate choices in a high-leverage situation in, say, the fourth or fifth inning. There is some missing context with that assumption such as availability and such, but the point becomes magnified in the postseason during a short series. For the Astros to succeed, Baker will need to aggressively utilize the bullpen, and that sometimes means bringing in one of your best to keep runs off the board in the fourth inning.

There is no question that the bullpen has regressed compared to last season’s performance and that development was expected to some degree. I mean, it is incredibly difficult to replicate something so good easily. Some of this downgrade is also explained by the overreliance on the bullpen as the rotation faltered earlier in the season. For as often as I separate starter versus reliever performance, their respective performances are influenced by usage. Maton, for example, was arguably overworked by June and his performance unsurprisingly suffered, at least for a time. It was also around this time when the rotation started to feel the ramifications of shortened outings and not enough arms to cover all of those innings. Winning the AL West, and securing that coveted bye, could perhaps allow his arm and others a bit of much-needed reprieve.

But if there is an area where this bullpen continues to excel as a continuation from 2022, it was consistently leaving runners on base. Since July 1, the Astros have led baseball with an impressive 80.8% LOB% from its relief corps, with Abreu, Graveman, and Neris leading the way. In other words, Houston has been truly adept at pulling a Houdini, if one could call it that. Having multiple relievers to rely upon with runners on base is a boon in a short series. It is also a key reason why this unit was such a quality one about preventing runs last postseason. For these Astros to repeat, they’ll need to continue their Houdini act for at least 11 more games.