That one inning pitched last night in Baltimore gives Mariano Rivera 1000.33 innings pitched for his career. By reaching this plateau, Rivera now qualifies for the all-time ERA and ERA+ leaderboards, according to Baseball-Reference.com. First, the classic statistic-- earned run average. Rivera now ranks 17th all time, tied with Jim Scott. Four of the pitchers ahead of Rivera had their careers end before 1900; the latest anyone ahead of him pitched was 1933 (some guy named Ruth), pitched seriously- 1927 (Walter Johnson).
If there's one thing the statistics revolution has taught me, it's that athletes are best judged relative to their peers. For while raw statistics are impressive, their true meaning only comes from studying how much better a great athlete was, compared to his competition. And so we reveal the new career adjusted ERA+ leader: Mariano Rivera. According to ERA+, Rivera has, since 1995, been 98 percent better than his peers, measured by ability to prevent earned runs. Rivera not only takes the top spot; he dominates it. Which raises the question: is Mariano Rivera the greatest pitcher of all time?
Clearly, mlb.com does not think a reliever should enter the discussion. Officially, to qualify for the career ERA title, one has to pitch 2000 innings, double the amount required by baseball-reference. A starting pitcher probably could eclipse the lower mark (1000 innings) in four or five full seasons; indeed Jake Peavy (7 seasons, 1202 IP) and Brandon Webb (6 seasons- 1235 IP) already grace the Active ERA leaderboard. But none of them have an ERA+ anywhere near the range of Mariano Rivera. Is his elevated ERA+ a factor of being a relief pitcher?
The short answer is: perhaps. Goose Gossage, whose recent election to the Hall of Fame might finally open the door for closers, finished with 1809 IP and an ERA+ of 126. All-Time saves leader Trevor Hoffman, who will soon match the 1000 IP plateau, has a career ERA+ of 144. Rather than try and name everyone; here is a list of all pitchers who relieved at least 80% of their games and threw at least 750 innings. Even with a lowered standard, only one other pitcher eclipses Pedro Martinez's record for career ERA+ by a starter (157)- Billy Wagner at 181. Rivera well out-paces Wagner's 181, although it lends some credence to the theory that relievers have inflated ERA+ that shouldn't be quantitatively compared to that of a lifetime starter.
Still, one has to expand the field to include all pitchers with 200 IP to find a single player who eclipses Rivera's ERA+ mark (and I didn't like who I found there either). Whatever the adjustment made to Rivera's numbers, due to his pitching role, it cannot completely erase how Rivera's peers have failed to come anywhere close to his production. Among pitchers with 1000 IP, Rivera is also in the top 25 in Strikeouts 9/IP, all time. Since 1995, no pitcher has prevented home runs better than Rivera. For fourteen seasons, Rivera has compiled a resume that I believe allows him to be compared with the starting pitchers, and statistically he rises as the best. And of course Rivera is, without a doubt the greatest relief pitcher of all time.
But if we can define "greatness" by performance relative to one's peers, no pitcher is greater than Mariano Rivera.
Who cares to challenge this?