Oakland’s Bullpen Has Been in Survival Mode

A pivotal series between the two teams atop the AL West kicked off on Tuesday with the Astros beating the A’s to extend their division lead to 4.5 games. It was an unusually shaky start from Chris Bassitt, who allowed six runs and couldn’t escape the fifth inning, but he turned the game over to Oakland’s bullpen with the game knotted at six runs apiece. The combo of J.B. Wendelken and Yusmeiro Petit, though, quickly changed that, allowing two runs in the sixth to put the A’s behind for good.

The A’s have routinely found ways to create value despite a small piggy bank, but the bullpen is probably the biggest concern with the team so far. That’s nothing unusual; most teams in the majors stress over their bullpen. But the A’s are not an ordinary team. During their current three-year streak of going to the playoffs, their bullpen has ranked in the top 10 in WAR each of those seasons and top five overall:

Team Bullpen WAR Leaderboard, 2018-20
TBR 1866.0 17.4 3.88 3.7
NYY 1464.2 17.2 3.89 3.85
SDP 1488.1 16.1 3.72 4.11
OAK 1428.2 15.6 3.9 3.48
MIN 1415.0 13.2 4.06 4.2
MIL 1513.1 12.8 3.95 3.99
HOU 1266.0 12.7 3.84 3.57
LAD 1395.2 10.6 3.87 3.59
CHW 1358.2 10.4 4.29 4.29
SFG 1428.2 9.3 4.02 3.89

So far in ‘21, though, Oakland is near the bottom of the league in bullpen WAR, ranking 24th. The main reason for the big step backwards: strikeouts. With Liam Hendriks and his hearty 39.9% strikeout rate at the helm last season, the A’s managed a 26.0% rate as a unit, good for eighth in the majors. This year, that’s all the way down to 20.1%; only the Diamondbacks have been worse. Losing Hendriks and Joakim Soria (25.0% strikeout rate last year) to free agency removed quite a few whiffs from the bullpen, but returning relievers this year have struggled to regain their swing-and-miss abilities from prior seasons.

Oakland Reliever Strikeout-Per-Nine Rates
Pitcher 2021 2020 Difference Career Average
Yusmeiro Petit 4.74 7.06 -2.32 7.95
Lou Trivino 8.26 10.03 -1.77 9.44
Jake Diekman 12.03 13.08 -1.05 11.34
Burch Smith 6.85 9.75 -2.90 9.51
J.B. Wendelken 8.04 11.16 -3.12 9.41

The performance by the group in the table above isn’t altogether bad. Trivino has done an admirable job stepping in to close games (13 saves in 15 opportunities) with a career-best ERA of 2.01 and a 3.70 FIP. But every single pitcher in the group has seen a significant drop in strikeout rate over last season.

To complicate things further, the A’s have used their bullpen less than every team in baseball except for the White Sox. It’s a stark difference compared to previous seasons; they tended to fall somewhere in the middle of the pack when it comes to bullpen usage over the last three seasons. Some of that is likely due to injuries. Their big offseason addition, Trevor Rosenthal, hasn’t thrown a pitch this season, and promising youngsters A.J. Puk and Jesús Luzardo are both in Triple-A after long stints on the shelf and struggles while on the field.

The A’s have been able to weather the storm with excellent pitching from the starting rotation, but not without cost. Oakland starters are seventh in the majors with 8.1 WAR to go along with a 3.69 ERA and 3.74 FIP, but they’ve also logged a league-leading 493 innings pitched. Coming into this season, only two of their five current starting pitchers had ever pitched more than 100 innings in a big league season: Sean Manaea and Bassitt.

Oakland Starting Rotation Innings Pitched
Pitcher 2021 IP Projected ROS 2021 IP Career High IP in a Season
Sean Manaea 97.2 183.0 160.2
Chris Bassitt 106.2 200.0 144.0
Cole Irvin 101.0 190.0 101.0
Frankie Montas 93.1 175.0 96.0
James Kaprielian 57.0 107.1 57.0
Stats are through Monday, July 6. Projected rest of season IP based on usage rate in ’21 season.

Other than Manaea and Bassitt, each starter in the rotation has either surpassed or is very close to surpassing his previous career high for innings pitched in a season. That’s a lot to ask from the staff for the entirety of a season; expect fatigue to set in in the second half.

The disparity between starters and bullpen usage will probably not continue. So far, 64.5% of innings pitched for Oakland have been by starters — a high number, but it’s an approach that teams have been successful with in the past. That strategy works best, though, with a star-studded rotation (like Cleveland in 2018 or Washington in ’19) or one with innings-eating veterans (like San Francisco in ’17).

Single Season SP Usage Rate Leaderboard, 2017-21
Season Team SP Innings Share
2018 CLE 68.2%
2017 WSN 67.3%
2017 CLE 66.0%
2017 SFG 66.0%
2018 HOU 65.7%
2017 ARI 65.3%
2020 CLE 65.2%
2019 WSN 65.2%
2019 CLE 64.7%
2021 OAK 64.5%

The A’s are walking the tightrope with their pitching. The rotation has masked a poor first half showing from the bullpen, and they can’t count on that continuing. And injuries have walled off any optimism that reinforcements are coming (at least internally) any time soon. Mike Fiers was shut down a few weeks ago after feeling discomfort in his throwing elbow; he’s avoided surgery up to this point, but he’s far from a return to action. Puk has a 9.27 ERA to go along with a 3.63 HR/9 in Triple-A. Luzardo’s ERA is even worse, and he lasted only two-thirds of an inning in his most recent start. And while Rosenthal hasn’t been ruled out to return at some point this season, he only just began baseball activities back on June 22; his road back is a long one.

Maybe this is a case of Oakland being Oakland. The A’s famously went against baseball trends during the Moneyball era; why should now be any different? As teams rely on relief pitching more than ever, the A’s are leaning on their rotation in a bigger way than ever before. Tuesday’s loss to the Astros could very well become the norm for this team, though, if the rotation slows down in the second half.

Chet is a contributor for FanGraphs. Prior to FanGraphs, he wrote for Purple Row. When not writing about baseball, he is a data scientist and outdoor sport enthusiast. He can be found on Twitter at @cgutwein.

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2 years ago

This inspired me to check out the IP charts and what jumps out is LAD with four arms in the top 21. That feels like something to watch in a full season after the short one.