This post was spurred by Joe Posnanski's piece on Mike Mussina's Hall of Fame case. Here:

Before [Gaylord] Perry (and Tom Seaver, Steve Carlton, Phil Niekro, Don Sutton and Nolan Ryan), winning 300 games was almost unheard of. Two post-World War II players had done it. One was the freakishly durable Warren Spahn. ... The other 300-game winner was Early Wynn, who won exactly 300 by just chugging along and chugging along...

Some part of me always thought, yeah, 300 wins, tough row but there's been quite a few. Nope, just 24, including five who did it in the 19th century. And between Sept. 1924 (Grover Cleveland Alexander) and August 1961 (Spahn)—or before Lindbergh crossed the Atlantic but after man orbitted the earth—there was just one guy who did it: Lefty Grove. And he hit 300 on the button.

The list:

Why the slowdown after the 1920s? I imagine WWII has something to do with it. Red Ruffing lost two years to the war (non-combat, four missing toes) and wound up with 273 career victories. Bob Feller lost four prime years to the war, years when he routinely won 20 games, and he finished with 266. Without the war, he'd probably have been in the rarefied 350+ territory. 

But what about our '60s guys? Yeah, there was still the draft. Whitey Ford lost two years to the military but it wouldn't have helped his 236 wins get over the magic mark. A sore shoulder forced Don Drysdale to retire young, at age 33, a year after he set the consecutive inning scoreless streak in 1968. He had 209 wins. Obviously Koufax, same, plus a long way away at 165. Jim Bunning stopped at 224, Juan Marichal at 243, Bob Gibson 251, Jim Palmer 268, Ferguson Jenkins 284. Even Fergie, who kept winning 20. That's how tough it is.

As for the guys that did it post-70s? Several things helped: the 162-game schedule (a few more games every year), Tommy John surgery, and just general fitness and personal training. Plus the spitter (Gaylord), the knuckler (Niekro), freakish durability (Nolan Ryan) and PEDs (??).

The last pitcher to make 300 was Randy Johnson, wearing a Giants uniform in 2009. Since then, the closest has been his one-time teammate, Jamie Moyer, who retired (at nearly 50!) with 269. The current active leaders are Bartolo Colon (240 at age 44) and C.C. Sabathia (237 at age 36). If C.C. has a second wind like Bartolo (87 wins since his age 36 season), he would do it; but it doesn't usually work that way. One man's second wind is another man's retirement. No other active pitcher has more than 200 wins.

Now we're not just in the era of the closer but the era of the bullpen. You want that sucker stacked. You want guys that can come in in the 8th or 7th or 6th. Or 5th? Or 2nd? All of whom might wind up with the W. So 300? We might not see its like again.