It turns out that Guidry's 161 ERA+ over a three year period is a pretty unusual achievement, so unusual that Guidry was only the third American League pitcher in the modern era (i.e., post-1920) to accomplish the feat. If you exclude the War Years (when Hal Newhouser did it) then Guidry was the first American League pitcher to turn the trick since Lefty Grove in the '30s.

We'll look at the select group of pitchers who've managed to maintain this level of dominance over a three-year span and examine the curious concentration of these achievements in two brief and distinct periods in baseball history.

Since 1920 there have been 15 pitchers to average a 160 ERA+ or better over a three year span. Only three pitchers accomplished it before WW II: Dazzy Vance, Lefty Grove and Carl Hubbell. Hal Newhouser did it from '44 to '46. Twenty years passed before Koufax and Marichal accomplished the feat from '64 to '66. Gibson did it from '68 to '70 and Seaver from '69 to '71. Guidry did it from '77 to '79. Clemens did it from '90 to '92. The explosion in offense over the last 15 years has produced a profusion of these dominant ERA+ performances, with Greg Maddux, Pedro Martinez and Randy Johnson averaging over 160 over more than a decade span, and Kevin Brown over a six-year span. Clemens did it a second time between '96 and '98. Johan Santana maintained a 160 ERA+ during the 5-year span between 2002 and 2006. Before this explosion in 160+ performances Lefty Grove had been the only pitcher in modern baseball history to maintain a 160 ERA+ for more than five years.

Of the 15 pitchers to accomplish this feat nine did it during two relatively brief and distinct periods: Koufax, Marichal, Gibson and Seaver did it during the era of pitching dominance from '64 to '71; Maddux, Brown, Martinez, Johnson and Santana have done it during the recent offensive heyday in baseball. This is not coincidental. The standard deviation in the distribution of ERAs during very low scoring and very high scoring periods tends to increase. During periods like the 1950's and 1980's, when scoring is more in line with the historical average for the 20th century, the standard deviation contracts.

Averaging a 160 ERA+ for a three year span is a tremendous achievement. Bunning and Drysdale never reached a 160 ERA+ for even a single season. Neither did Blyleven or Morris.

Again, to be clear, I am not arguing that any achievement or performance over a mere three-year period should be sufficient, in and of itself, to qualify one for the Hall of Fame. My purpose is to put into context Guidry's dominance during this period. He dominated to an extent few have, and in a way even many of the greats never did.