The Los Angeles Dodgers finished the regular season with the best record in baseball at 104-58. As a team, the Dodgers had thirteen different players finish above two wins above replacement and seven players with three wins above replacement. The top of the Dodgers' roster is filled with MVP candidates (Corey Seager, Justin Turner), all-star starting pitchers (Clayton Kershaw, Alex Wood), and breakout stars (Chris Taylor, Cody Bellinger).
Despite that impressive collection of everyday players and starting pitchers, the Dodgers closer Kenley Jansen, who pitched in just 68 1⁄3 innings over 65 games, finished with the sixth-highest WAR on the Dodgers, according to FanGraphs. On a historically great team, it took an equally historic season from Jansen to breach the top of the WAR list.
Jansen finished seventeenth-best among all pitchers — not just relievers! — at 3.5 wins above replacement. He finished alongside Yu Darvish and Michael Fulmer in WAR, who both pitched 186 2⁄3 and 164 2⁄3 innings respectively. He easily finished as the best relief pitcher in baseball by the same metric.
Jansen's 2017 season ranks among the best all-time for a relief pitcher. His 1.31 fielding independent pitching (FIP) ranks seventh-best ever among those with over 30 innings pitched in a single season. His 1.32 ERA ranks inside the top thirty among relievers who have thrown more than 60 innings in a single season. There are no flaws in Jansen's game pitching-wise.
His K/BB ratio was the third-best all-time among relievers with over 60 innings pitched. He allowed just five home runs all season, good for 0.66 HR/9. He induced an infield flyball percentage (IFFB%) of 23.2 percent, tenth-best ever among relievers. His soft-contact percentage of 31.7 percent ranked thirteenth all-time. Jansen strikes out a ton of guys, he doesn't allow hard contact, and he keeps walk and home runs to a minimum. He’s as close to perfect as a pitcher can get.
Despite Jansen's historically dominant season ratio-wise, his 2017 ranks just twenty-fourth all-time in wins above replacement among relievers. In that way, his season is a testament to how modern major league bullpens are being used, and to the limited utility they get from superstar relievers such as Jansen.
Once upon a time, it was extremely common for relief pitchers to throw over 100 innings in a season. In 1977, Bruce Sutter through 107 1⁄3 innings en route to the best single season of any relief pitcher ever, according to FanGraphs, at 5.2 wins above replacement. In 1974, Mike Marshall threw 208 1⁄3 innings over 106 games for the Dodgers. In 1980 alone, there were seventeen relief pitchers with over 100 innings pitched.
For better or for worse, bullpen management has changed drastically. Major league baseball hasn't seen a 100-inning relief pitcher since Scott Proctor did it in 2006 with the New York Yankees. Relievers have only breached the 100 inning mark in a single season six times since 2000. This year, just five relievers made it past the 80-inning threshold.
With just 68 1⁄3 innings this year, there is a question of whether Kenley Jansen is being fully utilized. He was used for more than an inning just fourteen times this year. He allowed an earned run in just one of those multi-inning appearances. He threw over thirty pitches in just one game this year and threw less than ten pitches on ten different occasions.
The Dodgers won the National League West by eleven games. They almost surely did not want to push Jansen to his physical limits during the regular season. But Jansen's possible underusage in a historically dominant season raises the question whether teams have overcompensated as far as rest goes for relief pitchers. If Jansen had gone two or even three innings more often in the regular season, would he be better prepared to shoulder that kind of load in a playoff emergency?
As starting pitchers go pulled earlier and earlier from games, bullpens inevitably will have more ground to cover. Super-relievers such as Jansen will need to take on more of the burden if the trend continues. The future of bullpen usage may look more like the late-seventies and early-eighties pretty soon.
Dylan Svoboda is a writer for Beyond The Box Score and BP Milwaukee. You can follow him on Twitter at @svodylan.