Over at the U.S.S. Mariner site, Marc W. wrote an excellent essay about bullpens. It's entitled "The M's Bullpen Bet" but it's only a little about the Seattle Mariners and mostly about bullpens in general. He writes:
This is a gross oversimplification, but I tend to think baseball and baseball analysts have two primary views of relief pitching. The first is leverage: sure, they don’t pitch as many innings as some random 4th starter, but the innings they DO pitch are often critical to wins and losses. A great reliever pitches effectively in high leverage situations, and thus helps his team win close games. Winning close games can be the difference between “contending” and celebrating, so, by this view, it’s not a surprise to see teams (especially in the AL, where every team’s clustered around average) focus on adding depth in the bullpen. The second overarching view of relievers is volatility. Sure, they’re highly leveraged innings, but the pitchers are so inconsistent that it’s kind of insane to give four years and $30m plus to a set-up man.
Marc's essay eventually leads to a few paragraphs about the 2016 Mariners. In 2014, the Mariners had a great bullpen, in fact led the majors in bullpen ERA. In 2015, the bullpen was terrible. Jerry Dipoto's means to improvement? Basically he's picked up a bunch of guys who weren't good in 2015 -- Steve Cishek lost his closer's job with the Marlins, Evan Scribner allowed 14 home runs in 60 innings for the A's (but had a 64/4 strikeout/walk ratio), Justin De Fratus had a 5.51 ERA with the Phillies, Cody Martin had a 7.92 ERA with the Braves and A's. Of the new relievers, only Joaquin Benoit, acquired from the Padres, had a good season, and he's 38.
Anyway, Dipoto is banking on the volatility of relievers. Maybe that group will be better in 2016. When I wrote about the Miami Marlins' bullpen on Thursday, I mentioned that improved bullpens are often a key to a surprising team's success. I provided a couple of anecdotal cases but I thought I'd look into it a little deeper. I checked all the teams over the past five seasons who went from under .500 to playoff contenders to see how much their bullpens improved.
Chicago Cubs: 73 to 97 wins
Bullpen ERA: 3.61 (15th in majors) to 3.38 (eighth)
Bullpen Win Probability Added improvement (from FanGraphs): +3.0 wins
Texas Rangers: 67 to 88 wins
ERA: 4.02 (24th) to 4.12 (24th)
WPA improvement: +5.1 wins
Houston Astros: 70 to 86 wins
ERA: 4.80 (30th) to 3.26 (sixth)
WPA improvement: +5.1 wins
New York Mets: 79 to 90 wins
ERA: 3.14 (eighth) to 3.48 (11th)
WPA improvement: +1.9 wins
Los Angeles Angels: 78 to 98 wins
ERA: 4.12 (26th) to 3.52 (14th)
WPA improvement: +5.2 wins
Seattle Mariners: 71 to 87 wins
ERA: 4.58 (29th) to 2.59 (first)
WPA improvement: +7.9 wins
San Francisco Giants: 76 to 88 wins
ERA: 3.30 (eighth) to 3.01 (fifth)
WPA improvement: +5.8 wins
Boston Red Sox: 69 to 97 wins
ERA: 3.88 (19th) to 3.70 (21st)
WPA improvement: +2.1 wins
Cleveland Indians: 68 to 92 wins
ERA: 3.99 (23rd) to 3.62 (19th)
WPA improvement: -1.0 win
ERA: 3.36 (11th) to 2.89 (third)
WPA improvement: +5.5 wins
ERA: 3.17 (sixth) to 2.55 (second)
WPA improvement: -1.7 wins
Baltimore Orioles: 69 to 93 wins
ERA: 4.18 (27th) to 3.00 (fifth)
WPA improvement: +9.8 wins
Oakland Athletics: 74 to 94 wins
ERA: 3.74 (18th) to 2.94 (fourth)
WPA improvement: +6.6 wins
Cincinnati Reds: 79 to 97 wins
ERA: 3.55 (11th) to 2.65 (first)
WPA improvement: +3.1 wins
Washington Nationals: 80 to 98 wins
ERA: 3.20 (fifth) to 3.23 (seventh)
WPA improvement: +0.3 wins
Arizona Diamondbacks: 65 to 94 wins
ERA: 5.74 (30th) to 3.71 (14th)
WPA improvement: +11.6 wins
Milwaukee Brewers: 77 to 96 wins
ERA: 4.48 (26th) to 3.32 (sixth)
WPA improvement: +2.8 wins
OK, I'm happy to report that my statement holds up. Of the 16 "surprise" teams, 14 of them had a higher Win Probability Added, some by a significant total. Does an improved bullpen explain all of the improvement? No, a better bullpen by itself won't be enough to drag a losing team into the playoffs without improvement in other areas.
It's interesting that some of the surprise bullpens faltered again the following season, like the 2015 Mariners, who went from No. 1 in bullpen ERA to 25th. The 2011-12 Brewers went from sixth in ERA to last as closer John Axford blew nine saves. The 2012 Orioles lost one game all season it led after eight innings; the 2013 team lost nine.
What does this mean for potential turnaround bullpens for 2016? I mentioned the Marlins because of the all the power arms they have in their bullpen but they also ranked 28th in the majors in bullpen WPA at minus-3.2 wins. Oakland's minus-7.8 WPA was the worst since the 2010 Diamondbacks. The A's are counting on a healthy Sean Doolittle but they also signed Ryan Madson and traded for Liam Hendriks, who both had quality 2015s. The Tigers were 19th in WPA and 27th in ERA and have added Francisco Rodriguez, Justin Wilson and Mark Lowe. Rodriguez keeps getting the job done even as his fastball velocity declines and Lowe has been injury-prone, but maybe the Tigers will finally have a decent pen. The Red Sox traded for Craig Kimbrel and Carson Smith after ranking 26th in relief ERA.
The Tigers and Red Sox wouldn't necessarily feel like surprise teams, but better bullpens will help their playoff chances. Improved relief efforts could also be what transforms the Marlins, Mariners and A's into playoff contenders. Hey, there's at least a couple of sub-.500 teams from the previous season that make the playoffs. I'd say those five teams are the best candidates to do that in 2016.