Mariano Rivera, postseason wizard

As Mariano Rivera embarked on his farewell tour during the 2013 season, writers and fans everywhere celebrated his career with a wide range of statistics and trivia. But this week, Sam Miller at Baseball Prospectus found a new way to put Rivera's postseason dominance in perspective. He wrote in a recent article:

It’s practically impossible for a pitcher to allow less than a run per nine innings.... So now think of Mariano Rivera’s postseason career as two seasons. The first goes from Oct 4, 1995 to Oct 18, 2001, and spans 71 innings. Rivera allows seven runs, six of them earned; 0.89 runs per nine, 0.76 ERA. The second “season” goes from Oct 21, 2001 to Oct 6, 2011, spans 70.1 innings. Rivera allows six runs, five of them earned; 0.77 runs per nine, 0.64 ERA.

The fact only one other pitcher since 1920 allowed less than one run per nine innings in a season (minimum 50 IP) only underscores Rivera's brilliance on baseball's biggest stage*. But, as fellow BP writer Jason Wojciechowski pointed out in the comments, there might be some "hidden" seasons: namely, a typical starting pitcher will throw close to 200 IP per season, so it seems likely that there will be some starters with 70 IP stretches where they allowed fewer than one run per nine innings. Today, I'm going to look at those starters.

* - I just want you to be aware: In 2019, someone will leave Mariano Rivera off their Baseball Hall of Fame ballot. That person will not necessarily use the "he played in the Steroid Era, and we have no way of knowing who was clean!" defense. But they might, so get ready for that.

For each pitcher, I counted the number of runs allowed over his last few starts, continuing to include additional starts until I had at least a 70-IP sample. I looked at entire starts, rather than breaking the starts down by inning; I expected that looking at intervals of exactly 70 IP will change the results, if only slightly. I moved one start at a time, so a single starter can have several of these intervals in one season.

Since 1946, there have been over 222,000 intervals of at least 70 IP spread between 2,122 starters. Of these, 87 different intervals have happened with fewer than one run allowed per nine innings (RA9). Because of the overlaps I discussed earlier, I found 40 unique occurrences of this feat (which I'll call a "Mariano") in my database. Let's explore those 40 a little more closely. First, we'll look at the lowest RA9 over a 70-IP stretch.

As might be expected, we see a number of famous performances on this list. The lowest RA9, for instance, comes from Bob Gibson's otherworldly 1968 season. I'm actually only using the minimum RA9 for each pitcher during their run, otherwise Gibson would dominate this table. We also see an entry from Orel Hershiser's 1988 where he threw 59 consecutive scoreless innings. But in my opinion, the two most impressive streaks belong to Ubaldo Jimenez (which included four starts at Coors Field, as well as road games in Phoenix and Houston) and Fernando Valenzuela (who had an RA9 under 1 for the first nine games of his career).

Next, let's see who kept their streak alive longest.

And again, Gibson's monster season is front and center. In fact, there are several streaks from the comparatively lower-scoring 1960s and a couple more from the post-Mitchell Report pitcher renaissance. Let's look at which years had the most Marianos. For this, we'll count streaks split between two seasons as a half for each:

I included the league RA9s for reference, so you could get a sense of how pitcher-friendly that season was. And with a stat like RA9, run environment will clearly play a big difference: an RA9 of one will be 77 percent better than league-average in the AL in 2010, but only 70 percent better than league-average in the AL in 1968.

To this point, we've only been discussing stretches of 70 IP, but remember: Rivera's career postseason numbers feature two consecutive Marianos. Rivera allowed fewer than one run per nine over 140 innings. Only two starters in our database had a similar run of 140 IP. The first, of course, is Bob Gibson in 1968, who had an RA9 of 0.92 over a 21-start stretch that season.

The second? Dean Chance. Of course. With the Angels in 1964, the 23-year-old Chance compiled an ERA of 1.65 (which translates to an ERA- of 48) and held batters to a .193 BA; Baseball-Reference.com estimates that Chance was worth 9.3 wins to a .500 Angels team. Needless to say, Chance won the Cy Young that year.

Outside of those two, only a select handful of pitchers have compiled two non-overlapping Marianos in their career. All five (Koufax, Marichal, Perry, Sutton, and Clemens) are or should be Hall of Famers.

I've uploaded a spreadsheet with the 70-IP and 140-IP information so you can look through it, and maybe be surprised by some of the names who did (Cal Eldred) and didn't (Pedro Martinez) achieve a Mariano. It provides another perspective as to how great Rivera was on baseball's biggest stage for nearly two decades.

. . .

All statistics courtesy of FanGraphs and Baseball-Reference. Special thanks to Sam Miller and Jason Wojciechowski for inspiring this article.

Bryan Cole is a contributor to Beyond the Box Score and will forever see Mariano Rivera in his nightmares. You can follow Bryan on Twitter at @Doctor_Bryan.

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