Edwin Diaz, Blake Treinen, and the Greatest Reliever Seasons Ever

Reliever performance is volatile, fluky even from year to year. One season, a closer is dominant; the next, he’s just average. Over the past 40 years, there have been 59 relief seasons of at least 3.0 WAR. Only Rob Dibble, Eric Gagne, Rich Gossage, Tom Henke, Kenley Jansen, and Craig Kimbrel have produced seasons of that standard consecutively. By comparison, 10 starting pitchers have exceeded 7.0 WAR in consecutive seasons (67 seasons total), and 10 position players have exceeded 8.0 WAR in consecutive seasons (83 seasons total). Those 59 relief seasons were compiled by 41 different relievers, and three of those seasons are happening right now.

Josh Hader’s second half hasn’t been as good as his first after a forgettable All-Star Game, but with a 1.83 FIP and a 2.08 ERA, Hader is right at 3.0 WAR. In a lot of seasons, a solid finish to the year would make Hader the highest-rated reliever by WAR. This year, however, Hader is solidly in third place behind Edwin Diaz and Blake Treinen.

A year ago, Diaz posted a 4.02 FIP and a 3.27 ERA. That’s not bad, but it’s also not great. Diaz struck out 32% of batters faced, which is quite strong, but he also walked 12% of batters and gave up 10 homers. This season, Diaz is using his slider a bit more to get swings outside of the zone. The results have been staggering: he’s increased his strikeouts by about 50% while decreasing his walks and homers by 50% as well. With a few weeks to go, Diaz has piled up 3.7 WAR thanks to a 1.38 FIP — or 34 FIP- when factoring in league and park, which allows us to compare across eras. Only four relievers have ever put up a FIP- that low: Wade Davis, Gagne, Jansen, and Kimbrel (twice). The increased specialization of the closer role means that those four players all come from the past 20 years. Although Diaz’s 1.95 ERA and 48 ERA- are very good, they are not the best marks in the game. That honor goes to Treinen.

The A’s reliever is part of an improbably successful bullpen that appears to be working miracles and has helped Oakland into playoff position. A year ago, Treinen split his time with the Nationals and A’s, recording a 3.42 FIP and 3.93 ERA. Like Diaz above, this made Treinen a decent, above-average reliever, but nothing close to a relief ace. This season, Treinen has added a 95-mph cutter and another mph to his fastball. Like Diaz, he increased his strikeout rate by about 50% — Treinen’s jump from 23% to 33% isn’t nearly as impressive — while keeping the same walk rate and seeing his home-run rate and BABIP fall precipitously. Treinen is pitching better than last season, but he’s also benefiting from a very good Oakland infield defense and a park that suppresses homers. Both of Treinen’s long balls this season have come on the road.

The combination of Treinen’s good pitching and Oakland’s defense — and, perhaps, a little bit of luck — means that only four relievers have ever posted an ERA- lower than Treinen’s current figure of 21: Zach Britton, Dennis Eckersley, Jonathan Papelbon, and Fernando Rodney. When you combine that run-prevention with a ton of high-leverage situations, you get one of the top Win Probability Added (WPA) seasons of all-time.

Most Reliever WPA in a Season
Year Name Team WPA -WPA WPA+ gmLI SD MD
1984 Willie Hernandez Tigers 8.58 -6.58 15.16 1.33 41 4
1980 Doug Corbett Twins 7.58 -11.59 19.16 1.73 35 7
1980 Dan Quisenberry Royals 7.09 -14.24 21.32 2.13 42 8
1975 Rich Gossage White Sox 6.94 -13.77 20.7 2.42 36 11
2000 Keith Foulke White Sox 6.62 -6.28 12.91 1.78 40 5
1996 Troy Percival Angels 6.54 -5.58 12.11 2.03 40 4
2016 Zach Britton Orioles 6.39 -3.63 10.03 1.67 42 1
2003 Eric Gagne Dodgers 6.32 -5.1 11.42 1.72 45 4
1979 Aurelio Lopez Tigers 6.19 -9.53 15.72 2.04 34 8
2018 Blake Treinen Athletics 5.97 -6.73 12.7 2.07 41 3

I think it’s fair to say that, when we think of great relievers, we consider some combination of performance, results, and situation. To that end, I compiled a list of relievers. I began with a sample of 3,617 relievers total who pitched at least 60 innings since 1871. I looked at the 84 player-seasons that featured a FIP- below 50, the 281 seasons that featured an ERA- below 50, and the 124 seasons where WPA was at least 4.0. There were 52 seasons meeting the ERA and FIP requirements. The lowest WPA was Tom Henke’s 1989 seasons, in which he somehow managed a 0.40 WPA with 24 shutdowns (WPA of at least .06) balanced out by 13 meltdowns (WPA of -.06 or worse). Adding in the WPA requirement left 23 seasons. Only Craig Kimbrel and Mariano Rivera appear on the list more than once, as the table below indicates.

Best Reliever Seasons Ever
Year Name Team IP WPA ERA ERA- FIP FIP-
2016 Zach Britton Orioles 67.0 6.39 0.54 13 1.94 44
2003 Eric Gagne Dodgers 82.1 6.32 1.20 30 0.86 19
2018 Blake Treinen Athletics 72.1 5.97 0.87 21 1.79 44
1998 Trevor Hoffman Padres 73.0 5.85 1.48 37 2.04 48
2004 Brad Lidge Astros 94.2 5.81 1.90 44 1.97 43
2017 Kenley Jansen Dodgers 68.1 5.57 1.32 32 1.31 31
1999 Billy Wagner Astros 74.2 5.32 1.57 36 1.65 37
2006 Jonathan Papelbon Red Sox 68.1 5.30 0.92 20 2.14 49
1993 John Wetteland Expos 85.1 5.28 1.37 34 1.85 46
1996 Mariano Rivera Yankees 107.2 5.26 2.09 43 1.88 40
1977 Bruce Sutter Cubs 107.1 5.18 1.34 31 1.61 39
2006 Joe Nathan Twins 68.1 5.05 1.58 35 1.68 39
2016 Andrew Miller – – – 74.1 5.04 1.45 34 1.68 38
2006 B.J. Ryan Blue Jays 72.1 4.76 1.37 30 2.14 47
1990 Dennis Eckersley Athletics 73.1 4.74 0.61 16 1.34 35
2013 Greg Holland Royals 67.0 4.65 1.21 30 1.36 35
2018 Edwin Diaz Mariners 69.1 4.59 1.84 46 1.39 34
2017 Craig Kimbrel Red Sox 69.0 4.48 1.43 31 1.42 32
2014 Dellin Betances Yankees 90.0 4.46 1.40 36 1.64 42
2008 Mariano Rivera Yankees 70.2 4.26 1.40 32 2.03 47
2012 Craig Kimbrel Braves 62.2 4.25 1.01 26 0.78 21
2013 Koji Uehara Red Sox 74.1 4.18 1.09 26 1.61 42
2011 David Robertson Yankees 66.2 4.09 1.08 26 1.84 44
Requirements: At least 60 IP, ERA- and FIP- below 50 and WPA of at least 4.0. Average is of WPA, RA9/WAR, and WAR.

Both Diaz and Treinen have time to add to their totals before the season. If we just wanted a reliever list sorted by WAR, it would look like this:

Best Reliever Seasons by WAR
Year Name Team IP ERA FIP WAR
1977 Bruce Sutter Cubs 107.1 1.34 1.61 5.2
1986 Mark Eichhorn Blue Jays 157.0 1.72 2.31 4.9
1979 Bruce Sutter Cubs 101.1 2.22 1.89 4.8
1979 Jim Kern Rangers 143.0 1.57 2.63 4.7
2003 Eric Gagne Dodgers 82.1 1.20 0.86 4.7
1974 Mike Marshall Dodgers 208.1 2.42 2.59 4.4
1990 Rob Dibble Reds 98.0 1.74 1.50 4.3
1996 Mariano Rivera Yankees 107.2 2.09 1.88 4.3
1977 Rich Gossage Pirates 133.0 1.62 2.50 4.2
1976 Rollie Fingers Athletics 134.2 2.54 2.29 4.1
1991 Duane Ward Blue Jays 107.1 2.77 1.74 4.1
1970 Tom Hall Twins 155.1 2.55 2.50 4.1
1975 Rich Gossage White Sox 141.2 1.84 2.62 4.0
2004 Brad Lidge Astros 94.2 1.90 1.97 3.7
1989 Rob Dibble Reds 99.0 2.09 1.71 3.7
2004 Francisco Rodriguez Angels 84.0 1.82 1.64 3.7
1988 Doug Jones Indians 83.1 2.27 1.84 3.7
2002 Eric Gagne Dodgers 82.1 1.97 1.80 3.6
2018 Edwin Diaz Mariners 69.1 1.95 1.38 3.7
1985 Bob James White Sox 110.0 2.13 2.36 3.6
1982 Rich Gossage Yankees 93.0 2.23 2.13 3.6
1999 Billy Wagner Astros 74.2 1.57 1.65 3.6
2017 Kenley Jansen Dodgers 68.1 1.32 1.31 3.6
1998 Robb Nen Giants 88.2 1.52 2.12 3.6
1986 Tom Henke Blue Jays 91.1 3.35 2.13 3.5
1989 Tom Henke Blue Jays 89.0 1.92 1.80 3.5
1983 Rich Gossage Yankees 87.1 2.27 2.33 3.5
2004 Eric Gagne Dodgers 82.1 2.19 2.05 3.4
1993 John Wetteland Expos 85.1 1.37 1.85 3.4
1991 Rob Dibble Reds 82.1 3.17 1.54 3.4
2006 J.J. Putz Mariners 78.1 2.30 1.73 3.4
2012 Aroldis Chapman Reds 71.2 1.51 1.55 3.3
2007 Rafael Betancourt Indians 79.1 1.47 2.22 3.3
2012 Craig Kimbrel Braves 62.2 1.01 0.78 3.3
1974 Rollie Fingers Athletics 119.0 2.65 2.28 3.3
1987 Dennis Eckersley Athletics 104.0 2.60 2.47 3.3
2017 Craig Kimbrel Red Sox 69.0 1.43 1.42 3.3
2004 B.J. Ryan Orioles 87.0 2.28 2.08 3.3
1987 Tom Henke Blue Jays 94.0 2.49 2.33 3.3
2018 Blake Treinen Athletics 72.1 0.87 1.79 3.3

If we want to incorporate runs and WPA, we can take the list of 23 players above and average WPA, RA9/WAR, and WAR. This might end up double-weighting the run-prevention aspect, but the requirement of 50 FIP- or lower filters out a lot of pitchers to potentially provide some balance. Here’s what those averages look like:

Best Reliever Seasons by WAR
Year Name Team IP WPA RA9-WAR WAR AVG*
1977 Bruce Sutter Cubs 107.1 5.2 5.8 5.2 5.4
2003 Eric Gagne Dodgers 82.1 6.3 4.4 4.7 5.1
1996 Mariano Rivera Yankees 107.2 5.3 4.5 4.3 4.7
2004 Brad Lidge Astros 94.2 5.8 4.2 3.7 4.6
2018 Blake Treinen Athletics 72.1 6.0 4.4 3.3 4.6
1998 Trevor Hoffman Padres 73.0 5.9 4.3 3.1 4.4
2006 Jonathan Papelbon Red Sox 68.1 5.3 4.8 3.1 4.4
1999 Billy Wagner Astros 74.2 5.3 4.0 3.6 4.3
2016 Zach Britton Orioles 67.0 6.4 4.0 2.5 4.3
1993 John Wetteland Expos 85.1 5.3 4.2 3.4 4.3
2017 Kenley Jansen Dodgers 68.1 5.6 3.5 3.6 4.2
1990 Dennis Eckersley Athletics 73.1 4.7 3.9 3.2 3.9
2008 Mariano Rivera Yankees 70.2 4.3 4.2 3.2 3.9
2006 Joe Nathan Twins 68.1 5.1 3.5 3.1 3.9
2016 Andrew Miller – – – 74.1 5.0 3.6 3.0 3.9
2017 Craig Kimbrel Red Sox 69.0 4.5 3.8 3.3 3.9
2018 Edwin Diaz Mariners 69.1 4.6 3.2 3.7 3.8
2014 Dellin Betances Yankees 90.0 4.5 3.8 3.2 3.8
2006 B.J. Ryan Blue Jays 72.1 4.8 3.9 2.7 3.8
2013 Greg Holland Royals 67.0 4.7 3.5 3.0 3.7
2012 Craig Kimbrel Braves 62.2 4.3 3.6 3.3 3.7
2013 Koji Uehara Red Sox 74.1 4.2 3.8 3.1 3.7
2011 David Robertson Yankees 66.2 4.1 3.7 2.6 3.5
Requirements: At least 60 IP, ERA- and FIP- below 50 and WPA of at least 4.0. Average is of WPA, RA9/WAR, and WAR.

*Average of WPA, RA9-WAR, and FIP WAR.

That Bruce Sutter season was something else. The split-finger pioneer had a higher WAR than CY Young-winner Steve Carlton in 1977, though both pitchers finished behind (in order) Steve Rogers, Rick Reuschel, Tom Seaver, Phil Niekro, and Burt Hooton. There might not be a best way to determine top reliever seasons, but the final method used here puts a Hall of Famer, a Cy Young winner, and a future Hall of Famer in the top-three. Diaz and Treinen both have some time to move their way up that particular list, but they are pretty clearly having two of the best seasons we’ve seen in the era of the modern reliever.

We hoped you liked reading Edwin Diaz, Blake Treinen, and the Greatest Reliever Seasons Ever by Craig Edwards!

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Craig Edwards can be found on twitter @craigjedwards.

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10 Comments on "Edwin Diaz, Blake Treinen, and the Greatest Reliever Seasons Ever"

newest oldest most voted
Kyle Tucker and Dale Vs. Evil
Member
Kyle Tucker and Dale Vs. Evil

But how would they do in space?

jmsdean477
Member
jmsdean477

all pitches would move very very straight over the types of distances that baseballs travel and they wouldn’t decelerate at all from the initial top speed, in fact they would continue to accelerate for some distance, over 60’6″. My more practical question is how would baseballs behave on mars with its lower gravity if the balls were 30% heavier to make up for it, after we terraform of course. Martian League Baseball where earth born players have like a 12′ vertical leap!