The normal values of batting average (BA), slugging percentage (SLG), and on-base plus slugging (OPS) have fluctuated over time:

In sum, no two seasons are alike, and some are vastly different from others. To level the playing field (pun intended), I did the following:

• Compiled single-season BA, SLG, and OPS data for all full-time batters (those with enough times at bat in a season to qualify for the batting title) from 1901 through 2015 — a total of 14,067 player-seasons. (Source: the Play Index at Baseball-Reference.com.)

• Normalized (“normed”) each season’s batting statistics to account for inter-seasonal differences. For example, a batter whose BA in 1901 was .272 — the overall average for that year — is credited with the same average as a batter whose BA in 1902 was .267 — the overall average for that year.

• Ranked the normed values of BA, SLG, and OPS for those 14,067 player-seasons.

I then sorted the rankings to find the top 25 player-seasons in each category:

I present all three statistics because they represent different aspects of offensive prowess. BA was the most important of the three statistics until the advent of the “lively ball” era in 1919. Accordingly, the BA list is dominated by seasons played before that era, when the name of the game was “small ball.” The SLG and OPS lists are of course dominated by seasons played in the lively ball era.

Several seasons compiled by Barry Bonds and Mark McGwire showed up in the top-25 lists that I presented in an earlier post. I have expunged those seasons because of the dubious nature of Bonds’s and McGwire’s achievements.

The preceding two paragraphs lead to the question of the commensurability (or lack thereof) of cross-temporal statistics. This is from the earlier post:

There are many variations in the conditions of play that have resulted in significant changes in offensive statistics. Among those changes are the use of cleaner and more tightly wound baseballs, the advent of night baseball, better lighting for night games, bigger gloves, lighter bats, bigger and stronger players, the expansion of the major leagues in fits and starts, the size of the strike zone, the height of the pitching mound, and — last but far from least in this list — the integration of black and Hispanic players into major league baseball. In addition to these structural variations, there are others that mitigate against the commensurability of statistics over time; for example, the rise and decline of each player’s skills, the skills of teammates (which can boost or depress a player’s performance), the characteristics of a player’s home ballpark (where players generally play half their games), and the skills of the opposing players who are encountered over the course of a career.

Despite all of these obstacles to commensurability, the urge to evaluate the relative performance of players from different teams, leagues, seasons, and eras is irrepressible. Baseball-Reference.com is rife with such evaluations; the Society for American Baseball Research (SABR) revels in them; many books offer them (e.g., this one); and I have succumbed to the urge more than once.

It is one thing to have fun with numbers. It is quite another thing to ascribe meanings to them that they cannot support.

And yet, it seems right that the top 25 seasons should include so many of Ty Cobb’s, Babe Ruth’s, and of their great contemporaries Jimmie Foxx, Lou Gehrig, Rogers Hornsby, Shoeless Joe Jackson, Nap Lajoie, Tris Speaker, George Sisler, and Honus Wagner. It signifies the greatness of the later players who join them on the lists: Hank Aaron, George Brett, Rod Carew, Roberto Clemente, Mickey Mantle, Willie McCovey, Stan Musial, Frank Thomas, and Ted Williams.

Cobb’s dominance of the BA leader-board merits special attention. Cobb holds 9 of the top 19 slots on the BA list. That’s an artifact of his reign as the American League’s leading hitter in 12 of the 13 seasons from 1907 through 1919. But there was more to Cobb than just “hitting it where they ain’t.” Cobb probably was the most exciting ball player of all time, because he was much more than a hitting machine.

Charles Leershen offers chapter and verse about Cobb’s prowess in his book Ty Cobb: A Terrible Beauty. Here are excerpts of Leershen’s speech “Who Was Ty Cobb? The History We Know That’s Wrong,” which is based on his book:

When Cobb made it to first—which he did more often than anyone else; he had three seasons in which he batted over .400—the fun had just begun. He understood the rhythms of the game and he constantly fooled around with them, keeping everyone nervous and off balance. The sportswriters called it “psychological baseball.” His stated intention was to be a “mental hazard for the opposition,” and he did this by hopping around in the batter’s box—constantly changing his stance as the pitcher released the ball—and then, when he got on base, hopping around some more, chattering, making false starts, limping around and feigning injury, and running when it was least expected. He still holds the record for stealing home, doing so 54 times. He once stole second, third, and home on three consecutive pitches, and another time turned a tap back to the pitcher into an inside-the-park home run.

“The greatness of Ty Cobb was something that had to be seen,” George Sisler said, “and to see him was to remember him forever.” Cobb often admitted that he was not a natural, the way Shoeless Joe Jackson was; he worked hard to turn himself into a ballplayer. He had nine styles of slides in his repertoire: the hook, the fade-away, the straight-ahead, the short or swoop slide (“which I invented because of my small ankles”), the head-first, the Chicago slide (referred to by him but never explained), the first-base slide, the home-plate slide, and the cuttle-fish slide—so named because he purposely sprayed dirt with his spikes the way squid-like creatures squirt ink. Coming in, he would watch the infielder’s eyes to determine which slide to employ.

There’s a lot more in the book, which I urge you to read — especially if you’re a baseball fan who appreciates snappy prose and documented statements (as opposed to the myths that have grown up around Cobb).

Cobb’s unparalleled greatness was still fresh in the minds of baseball people in 1936, when the first inductees to baseball’s Hall of Fame were elected. It was Cobb — not Babe Ruth — who received the most votes among the five players selected for membership in the Hall.