The Orioles and the Most Influential Bullpen

Wei-Yin Chen gave up two runs in just 5.1 innings Tuesday against the Mariners. The next 12.2 innings all belonged to the Baltimore bullpen. Their response? Six hits, four walks, 16 strikeouts and zero runs, with all but one of those 12.2 innings requiring a shutout just to keep the game going.

As a result, Steve Johnson, Darren O’Day, Tommy Hunter, Jake Arrieta, Pedro Strop, Jim Johnson and Brian Matusz combined for a massive 1.170 WPA on the game. The Orioles bullpen now owns a 12.51 WPA for the whole season, with yesterday’s performance enough to push them over the 1984 Tigers for the highest season bullpen WPA since our reports carry the data (back to 1974). Judging by the historical data, this Orioles bullpen has been the most influential in recent major league history.

The 1984 Tigers bullpen largely featured Willie Hernandez‘s dominance — a +8.58 WPA on the back of 140.1 IP with a 1.92 ERA and 2.58 FIP. Hernandez went on to win the MVP that year for the eventual World Series champions as the club topped the American League at 104-58. Hernandez was most certainly not the only influential player on that team. The club’s worst wRC+ from a player with at least 160 PA was Tom Brookens’s 93. Alan Trammell (137 wRC+, 7.3 WAR), Chet Lemon (133 wRC+, 6.6 WAR) and Kirk Gibson (145 wRC+, 5.2 WAR) were elite players as well. This was a team with playoff destinies even without Hernandez, most likely.

We can’t have such confidence about the Orioles, whose success has mystified analysts and fans alike for much of the season. But how they’re winning isn’t much of a mystery — when they grab a late lead, they hold on for dear life behind a bullpen that has been especially good in the back end. Jim Johnson has just three meltdowns against 42 shutdowns. Darren O’Day has held righties to a .199/.268/.333 line and owns a 2.47 ERA. Pedro Strop has a 2.27 ERA behind a heavy sinking fastball, generating 65.1% ground balls. These three combined have 9.21 of the Orioles’ total 12.51 WPA. This trio is, at least in terms of game influence and results, the Orioles’ version of Willie Hernandez in 1984.

It’s not the best bullpen ever. Baltimore’s 3.05 ERA is just sixth this year behind the Royals, Athletics, Braves, Rays and Reds, nearly a half-run behind Cincinnati. Their 3.75 FIP is 14th. On pure runs allowed or peripherals, this is nothing we haven’t seen before. But they save their best for the biggest moments. Only the Rays have allowed a lower wOBA against in high leverage situations, and not by much — .250 to Baltimore’s .258. O’Day is at .179, Johnson at .198, and Strop at .245; all three are above .260 in low-leverage situations. The Orioles bullpen has five of the top-35 pitchers in high leverage situations this season.

How does a team win when they’re outscored overall? Those times they are staked to a lead, they have to hold on. Cling for dear life as potential disaster after potential disaster come and pass. The Mariners opened two of the extra frames on Tuesday with doubles, and the Orioles stranded each one. The Mariners helped, to be sure, with failed bunts and poor at-bats. But the Orioles’ relievers did exactly what they’ve been doing all year — whatever it takes to keep their team alive or ahead. So maybe they’re not the best ever, on merit or talent. But they’re definitely one of the most important bullpen units we’ve ever seen.