Enter the Lefties

Tom Glavine, with 294 wins, is on the verge of becoming only the fifth lefthanded pitcher in Major League history to win 300 games (Randy Johnson, if he manages 20 more wins, would be the sixth). Which leads me to an interesting issue: the fact that it took some time for lefthanded pitching to take root in the majors. While this story would make a fascinating article by someone with more time to do the research, I’ll lay out here the outlines in statistical terms.
Over the first 11 years of major league ball – the five year run of the National Association from 1871 to 1875, and the first six years of the National League from 1876 to 1881 – lefthanded pitchers were at best a curiosity:

Granted, there were a few hundred innings thrown over those years by pitchers whose handedness was not recorded, but those were rarely guys with significant pitching roles. In both 1874 and 1876 there was no lefthanded pitching at all.
Those 2,586 innings were thrown by just 11 men, three of whom (Charlie Pabor, Ed Pinkham, and Hall of Fame slugger Dan Brouthers) were full-time players who never threw more than 30 innings in a season, and three others of whom (John McMullin, John Cassidy and Curry Foley) also spent the bulk of their careers as everyday players, plus two (Jack Leary and John Greason) who never pitched as many as 70 innings in a season.
If there is a common thread among the earliest southpaws, it’s that they were ineffective. McMullin threw 249 innings for Troy in 1871, the first lefty to play a significant pitching role, and was pounded, walking a league-leading 75 batters (an astoundingly high total for the day) and finishing with the worst ERA of any significant pitcher in the league. He spent most of the rest of his career as an outfielder. Next up in 1875 was John Cassidy, who was likewise spectacularly ineffective in 214.2 innings for Brooklyn and who likewise set off on a career in the outfield.
The first semi-significant lefty in the National League, and the first to spend his career primarily as a pitcher, was Bobby Mitchell, who threw 100 innings for Cleveland in 1877, 80 for Cincinnati in 1878, and 194.2 for Cleveland in 1879. Though ERAs were not tracked in those days, Mitchell never did manage a league-average ERA and ended with a losing record, but he at least pitched respectably, and had the highest K/IP rates in the NL in 1877 & 1878. In 1879 he was joined by Foley, an OF-1B who threw 161.2 innings in 1879 and 238 in 1880, both for Boston, with middling results. But most teams in those days used a single starter to handle most of the work, and in 1880-82, the first lefty to take that job emerged, as Lee Richmond threw 590.2, 462.1 and 411 innings for Worcester. Richmond pitched well his first season, but the Worcester Ruby Legs finished last in 1881 and 1882, so he didn’t exactly inspire a rush of imitators.
In 1882, however, something new happened: the American Association sprang up as a rival major league. The first ERA champ in the league was 21-year-old lefty Denny Driscoll, who got a full-time rotation gig the following year. And then in 1884, a sea change set in: the rules were liberalized to allow pitchers to throw overhand. I have to believe that the ability to abandon straight underhand was the change that made lefthanders proportionately more effective, and the AA was the early adopter (as startup leagues are often quicker to process innovation): the first lefty to lead a league in IP or K was Ed Morris in the AA in 1885 (his second season as a rotation anchor, at age 22), the first in Wins was Morris in 1886, and lefties led the AA in innings and strikeouts from 1885-87, with young fireballers Matt Kilroy (age 20, 513 K) and Toad Ramsey (age 21, 499 K) posting the two highest strikeout totals of all time. The unfortunately nicknamed Lady Baldwin became the first star lefty in the NL, posting a 1.86 ERA in 1885 and going 42-13 while leading the league in wins and strikeouts in 1886.
Even so, significant lefthanded pitching was still a relative rarity through the end of the 1800s. While multiple righthanded pitchers racked up large career win totals, only six 19th century lefties won as many as 100 games: Morris with 171, followed by Frank Killen (164), Ted Breitenstein (160), Kilroy (141), Ramsey (114), and Duke Esper (101). One can look at the records of lefthanded hitters in this era and see, perhaps, the benefits of the relative dearth of lefthanded quality pitchers.
The end of the 19th century brought on the two men who would set the template for lefthanded pitchers to follow, and they plied their trade once again mainly in an upstart league, the American League. First came Rube Waddell, baseball’s second pitcher (after Amos Rusie) to compile a multi-year record as a strikeout pitcher. Waddell, of course, was an eccentric, childlike, unpredictable drunk and – Bill James suggests – possibly mentally disabled, and likely contributed as much as anyone to the stereotype of the flaky lefthander. His teammate Eddie Plank, by contrast, was more like Glavine, a cerebral, college-educated pitcher who set the mold of the crafty lefthander. Together they brought a lot of success to Connie Mack, and Plank became the first lefty to win 300 games – indeed, the first to win 200 games. With 305 of his 326 wins coming in the AL, he holds to this day the career record for wins by an AL lefty.
As we know, the concept of platooning first began to be tried around 1906, though it did not come into heavy vogue until around 1920 – which was around the time that the emergence of Babe Ruth created a much more pressing need for teams to find their own Hub Pruett type lefties who could shut down the Babe. By 1919, the career leaderboard for lefties looked like this (and recall that by this point Walter Johnson was three wins from becoming the ninth righthanded 300-game winner, including five with 340 or more wins; counting wins in the NA, there were by then 14 righties with 250 or more wins, 24 with 225 or more). A few of these guys, as you can see from their career timelines, would win a few more in the 1920s; Marquard would become the second lefty to win 200 games, and two others who would as well (Eppa Rixey and Wilbur Cooper) were already active.

You can see how Plank towered over his contemporaries . . . I haven’t crunched the numbers to see how the proportion of lefties increased over time from the 1880s or when it reached modern rates, but by 1920, besides the above, there were a number of other active lefties on their way to decent careers, and in 1925 Mack came up with his third lefty superstar, Lefty Grove, who would go on to become the second lefty to win 300 games, followed by Warren Spahn (now the winningest lefty of all) and Steve Carlton. Today there are 25 lefthanded pitchers who have won 200 games, including 10 who have won 250 or more, compared to 83 righthanded 200-game winners, 34 righthanded 250-game winners, and 18 righthanded 300-game winners. I’ll close with the top 10 winningest lefties of all time as of yesterday’s action: