Highest Leverage Index of All Time
...Or at least 1954, the years retrosheet has play by play files for.
I sorted my career pitcher log by career leverage index, which measures the volatility of a game (1 is average, 9th inning, 1 run lead is high, 7th inning, 12 run lead is low). Since there are some pitchers who came up for a cup of coffee, might have for some emergency found themselves in a crucial sitation, and never pitched again, I was expected to see a lot of 2-5 inning guys before I got to the real careers.
In reality, there are only a few of them. Bruce Sutter ranks 8th with a 2.0 leverage index, behind 7 guys who pitched no more than 3 innings each. A few pitchers come in at 1.9, K-Rod, Percival, John Franco, and Trevor Hoffman among them. Mariano Rivera is at 1.8.
Only one pitcher has a leverage index of 3.0, hitting that on the nose. Surprise is, it wasn't even a real pitcher, but catcher Brent Mayne for one inning on August 22, 2000. The game between the Rockies went 12 innings, and the Rockies had already used 9 pitchers before handing the ball to Mayne. I don't remember the whole story, maybe the last guy got hurt and Mayne had to pitch since there was nobody left. The 6 pitchers before him didn't work very hard, throwing between 3 and 12 pitches each.
Anyway, Mayne faced Tom Glavine and got a ground out. Walt Weiss flew out to center. This pitching stuff ain't that hard, is it? A single, wild pitch, and walk later, Mayne found himself staring down the reigning NL MVP, Larry Wayne Jones, who had already homered in the game. No big deal, Jones grounded out to third, the Rockies won the game in the bottom of the inning, and Mayne's legend as the most leverage pitcher of all time was established.