Reading this topic I got very interested in ERA+, and whether it can be anything close to a one-size-fits all stat to measure reliever performance. Not sure I'm any closer, and definitely sure I'm not really qualified to make that call anyway. But just for general interest, and in how it relates to Koji's season, I thought there were some pretty fascinating trends.
Strictly by ERA+ (minimum 40 IP seemed reasonable), Koji's not in the top 20 best seasons, but damn close. He's at #26, with an ERA+ of 331.
300 seems like a good cut-off for the elite of the elite seasons. It's only been done 44 times.
Whether Koji makes the top 20 this year will depend not only on his performance, but on the 5 other pitchers above 300 this year who could beat him out or drop behind him. Mark Melancon, whose name sounds familiar (387) and Craig Kimbrel (370) are ahead, and Neal Cotts (328), Luis Avilan (327) and Alex Torres (302) are behind. That's crazy. 6 would be easily the most for a single season (4 in 2006, 07 and 08) but the overall trend stands out even more. If this year stands, 12 of the top 44 (27%) will have been in the last 3 years. And 31 (71%) will have been since 2000, and 37 (84%) since 1990. There were only 2 seasons in the 70's (Bruce Sutter in 1977, Dale Murray in 1974), and 1 in the 60's (Bill Henry in 1964)! Obviously reliever usage has changed, so it's not surprising it's skewed toward recent years, but I'm amazed it's that skewed. Maybe it means that ERA+ isn't really as adjusted as it would seem...I'll leave that for the experts. Or maybe that the most elite relievers now are just really, really good. Seems possible.
Into trivia now, but thought this was cool:
Top 5: Joey Devine, OAK in 2008 (698); Fernando Rodney, TBR in 2012 (641); Dennis Eckersley, OAK in 1990 (603); Rob Murphy, CIN in 1986 (541); Jonathan Papelbon, BOS in 2006 (517).
If Craig Kimbrel does it again this year, he will be the only pitcher to beat 300 twice, other than Mariano Rivera (also twice). He would be the only one to do it two years in a row (403 last year).
With numbers this low, obviously a single HR can make a huge difference. Devine gave up none in 2008 ...if he gives up 1 more earned run, his ERA+ drops from 698 to something like 535 (I think...I don't know exactly how the ballpark adjustment works). Also, a lot of guys were really "helped" by unearned runs. 4 out of 7 of Devine's total runs allowed were unearned...and lots of other similar cases.
Atlanta has had the most seasons above 300, with 6. Second, Montreal with 5. Boston, 3 (counting this year).
Besides Uehara (if he does it), and Papelbon in 06, who's the other Red Sox to top 300?
Uehara would be the oldest pitcher (38) to beat 300, tied with Rivera.
Only in 6 of these seasons did the player lead the league in saves.
And for the paranoid...the Sox have also had a lot of players who had fantastic seasons before or after coming to Boston. That list includes Eric Gagne (2003), Uggy Urbina (1998), Eckersley (1990), Melancon, and Cla Meredith (2006).