I am an unabashed Mariano Rivera fan. He’s probably my favorite player of all time who isn’t named Mattingly. And I have reflected a lot over the years about his surpassing greatness. Calling him the greatest reliever of all time doesn’t do it justice. With all due respect to Goose Gossage or Trevor Hoffman or Hoyt Wilhelm or whoever else might be second, he is so much better than any other reliever that somehow we need a different lens to view him through.
One way that I have thought about it is to try to conceive of how a reliever could be better than Mariano Rivera. Is that even possible? What would the characteristics of such a player have to be? You could take Mariano’s career stats and then create an imaginary player who improves on all of them by 10%, but somehow that doesn’t really help to answer the question of whether it’s realistic to think there could be such a player. I think a better way to think about it is to try to answer this question: has any reliever ever established a sustained level of performance, over multiple years, that is better than Mariano’s standard level of performance? If so, then at least there is a foundation for how a reliever could be better than Mo, if he could sustain that performance over a longer period of time.
To try to answer that question, I looked for the greatest sustained peak stretches of relief pitching in history, where a sustained peak is defined as of at least 3 consecutive years of pitching that is at least in the neighborhood of Mariano’s average level. I was able to find 19 such stretches:
- Goose Gossage 1975, 1977-1985
- Trevor Hoffman 1996-2001
- Billy Wagner 1999, 2001-2006
- Joe Nathan 2004-2009
- Francisco Rodriguez 2004-2008
- Keith Foulke 1999-2004
- Jonathan Papelbon 2006-2009
- Dennis Eckersley 1987-1992
- Bruce Sutter 1976-1980
- John Wetteland 1993-1998
- Troy Percival 1995-1997
- Craig Kimbrel 2012-2017
- Kenley Jansen 2013-2017
- Dan Quisenberry 1980-1985
- Hoyt Wilhelm 1961-1965
- Aroldis Chapman 2012-2016
- Eric Gagne 2002-2004
- Zach Britton 2014-2016
- Joakim Soria 2007-2010
Then I compared those stretches to Mariano’s entire career, excepting 1995, when he was a starter, and 2012, when he was injured.
In a couple of cases, I allowed a skip year. Wagner 2000 and Mariano 2012 were injury years, so I left them out. Gossage 1976 was the year where Paul Richards tried to make him a starter, so I threw that out.
To measure the quality of each reliever, I used the following stats (all data from fangraphs):
- Average WAR
- Average WPA
- Average RE24
- Average WPA/LI
- ERA-
I then stack ranked each statistic individually 1-20 and added the stack ranks together to create a cumulative score for each reliever. The best possible score would be 5; the worst would be 100.
There is nothing magical about this particular selection of statistics for measuring reliever quality. WPA seems to be a favored statistic for reliever, and I understand why, but I think it’s important to balance that with some non-contextual stats, for one simple reason: a reliever largely does not control his context. For that reason, it doesn’t seem fair to evaluate a reliever completely on context-dependent stats. So I created a blended statistic combining content-dependent and context-independent stats.
Anyway, here are the results:
| Player | Year | # Seasons | WAR Avg | WPA Avg | RE24 Avg | WPA/LI Avg | ERA- Avg | WAR Rank | WPA Rank | RE24 Rank | WPA/LI Rank | ERA- Rank | Total Score |
| Eric Gagne | 2002-2004 | 3 | 3.90 | 5.78 | 24.93 | 2.73 | 45 | 1 | 1 | 2 | 1 | 4 | 9 |
| Joe Nathan | 2004-2009 | 6 | 2.37 | 4.00 | 23.19 | 1.97 | 42 | 8 | 4 | 4 | 7 | 3 | 26 |
| Jonathan Papelbon | 2006-2009 | 4 | 2.45 | 3.98 | 22.96 | 1.86 | 38 | 7 | 5 | 5 | 10 | 2 | 29 |
| Zack Britton | 2014-2016 | 3 | 1.87 | 4.34 | 23.24 | 2.12 | 34 | 18 | 2 | 3 | 5 | 1 | 29 |
| Keith Foulke | 1999-2004 | 6 | 2.12 | 3.33 | 25.71 | 2.20 | 52 | 14 | 12 | 1 | 2 | 12 | 41 |
| Mariano Rivera | 1996-2011, 2013 | 17 | 2.25 | 3.29 | 20.56 | 1.91 | 45 | 9 | 13 | 8 | 8 | 4 | 42 |
| Goose Gossage | 1975, 1977-1985 | 10 | 2.73 | 3.66 | 20.30 | 1.78 | 54 | 3 | 9 | 9 | 12 | 15 | 48 |
| Dennis Eckersley | 1987-1992 | 6 | 2.55 | 3.24 | 20.26 | 2.14 | 53 | 6 | 15 | 10 | 3 | 14 | 48 |
| Dan Quisenberry | 1980-1985 | 6 | 1.92 | 3.88 | 21.75 | 2.13 | 61 | 16 | 6 | 7 | 4 | 19 | 52 |
| Billy Wagner | 1999, 2001-2006 | 7 | 2.16 | 3.54 | 19.27 | 1.88 | 47 | 13 | 11 | 13 | 9 | 8 | 54 |
| Troy Percival | 1995-1997 | 3 | 1.93 | 3.87 | 22.85 | 1.67 | 52 | 15 | 7 | 6 | 14 | 12 | 54 |
| Bruce Sutter | 1976-1980 | 5 | 3.22 | 3.25 | 19.45 | 1.84 | 60 | 2 | 14 | 12 | 11 | 17 | 56 |
| Joakim Soria | 2007-2010 | 4 | 1.75 | 4.07 | 18.88 | 1.52 | 45 | 20 | 3 | 14 | 16 | 4 | 57 |
| Craig Kimbrel | 2012-2017 | 6 | 2.23 | 3.04 | 16.03 | 1.52 | 45 | 10 | 16 | 16 | 17 | 4 | 63 |
| Francisco Rodriguez | 2004-2008 | 5 | 2.22 | 3.59 | 16.61 | 1.51 | 50 | 12 | 10 | 15 | 18 | 10 | 65 |
| Trevor Hoffman | 1996-2001 | 6 | 2.23 | 3.69 | 15.51 | 1.76 | 60 | 10 | 8 | 18 | 13 | 17 | 66 |
| Aroldis Chapman | 2012-2016 | 5 | 2.58 | 2.44 | 15.76 | 1.51 | 47 | 4 | 19 | 17 | 19 | 8 | 67 |
| Kenley Jansen | 2013-2017 | 5 | 2.56 | 2.98 | 14.75 | 1.57 | 54 | 5 | 17 | 20 | 15 | 15 | 72 |
| Hoyt Wilhelm | 1961-1965 | 5 | 1.86 | 2.32 | 20.18 | 2.04 | 61 | 19 | 20 | 11 | 6 | 19 | 75 |
| John Wetteland | 1993-1998 | 6 | 1.90 | 2.63 | 15.46 | 1.48 | 50 | 17 | 18 | 19 | 20 | 10 | 84 |
I would group these into 3 categories. Keep in mind, we are comparing these relievers’ peaks with Rivera’s average.
1) Definitely better than Mariano – Gagne, Nathan, Papelbon, Britton
2) Similar to Mariano’s level, and would at least have an argument – Foulke, Gossage, Eckersley, Quisenberry, Wagner, Percival, Sutter, Soria
3) Really good, but not at Mariano’s level – Kimbrel, K-Rod, Hoffman, Chapman, Jansen, Wilhelm, Wetteland
From this, I conclude that four relievers have succeeded at establishing a level that was, for a sustained period of time, better than Mariano’s average.
1) Gagne 2002-2004. I don’t think there can be any argument that Gagne’s 2002-2004 level of performance represents the greatest three-year stretch of relief pitching in the history of baseball.
2) Britton 2014-2016. Almost as good as Gagne. Only his WAR is dragging him down, which is probably an anomaly of some kind. WAR for relief pitchers is a bit sketchy anyway.
3) Papelbon 2006-2009. Incredible. He had other good years, but there was clearly a drop-off in performance after 2009 where he went from elite to just good.
4) Nathan 2004-2009. I have to admit that I found this surprising. I knew Nathan was good, but I didn’t know he was this good. It’s worth noting that he got hurt in 2010 and had TJ surgery. After the injury, he worked his way back to one more great season in 2012 at age 38 before finally dropping off the cliff.
So where does that leave us? The longest period where any reliever has been better than Mariano is Joe Nathan from 2004-2009. IF he hadn’t gotten hurt and had maintained the same level of performance through 2012, and IF he had been moved to the bullpen prior to age 28, then maybe, just maybe, you have a reliever who could challenge Mariano.
Of course I am leaving aside the whole subject of postseason performance, which is another massive element of Mariano’s greatness. Even 14 years of Joe Nathan’s best probably isn’t enough to make up for Mariano’s postseason heroics, but it would be a good debate.