Koufax's last four seasons, '63-'66, were as dominant as any pitcher ever was, at least in my lifetime. And he was almost as good in '61 and '62. But a pitcher whose sustained greatness isn't recognized enough is Randy Johnson. Johnson's excellent career win-loss percentage is .646, comparable to Koufax's .655, but Johnson did it for 22 seasons. Koufax had 2,396 career strikeouts in 2,326 innings, while Johnson had 4,875 in 4,135 innings and was still averaging close to a strikeout per inning in his mid-40s!
Nolan Ryan is the most remarkable power pitcher in baseball history, but not the best because of his W-L record (324-292).
The 1960s and '70s was a Golden Age of pitchers, one we won't see again because of five-man starting rotations and the specialization of relief pitchers. Give me 300 inning, 20 game winners with 20+ complete games any day of the week. And of course even they pale by comparison to the workhorse pitchers of the early 20th century.
In total agreement with you about Randy Johnson, Don. He was the most overpowering and purely dominating pitcher I ever saw, as well as scarier than any pitcher this side of Ryne Duren and Steve Dalkowski (though, of course, they weren't in Johnson's league for greatness). The one reservation I have about Randy is the same reservation I have about Kershaw, Pedro, Clemens, and Verlander: they all pitched in a steroid-soaked era. Did Randy take steroids? We'll never know, but they were so prevalent during his time that it cannot possibly be ruled out, and there are many baseball insiders who believe he did. And I do not trust MLB when they say PEDs are no longer in the game today.
I have no problem with anyone who chooses to rank Randy or Clemens above Walter Johnson, Koufax, or any of the other great earlier pitchers. I absolutely understand that position. I even understand those who rate Barry Bonds above everyone but Ruth or Cobb (but I hope no one goes THERE - not above the Peach or the Bambino). True, we
know Bonds and Clemens used, but the silence around other greats of that era doesn't preclude
their using, either. The only pitcher of that era I feel completely confident about was Greg Maddux, but Maddux was a genius of another kind, perhaps the greatest pure pitching
artist ever.
Since historians generally agree that the mainstream advent of the steroid era in baseball was about 1990, give or take a couple of years, I tend to classify everyone whose peak years occurred during that time or afterward as players of The Steroid Era. If I had my way, there'd be two separate record books: one book for those whose peak years occurred prior to 1990, and another for those whose peak years came after. And I'd have two separate wings in the Hall of Fame, as well. I know that this is not a popular position, but there's no danger of that happening anyway. But in my own mind, Rose will always be the all-time hit leader; Aaron the home run leader; Hornsby, the single-season BA leader, etc.
If I
must consider the two eras together, as one whole, rather than separately as is my preference then, yes, I'd say Randy Johnson is the greatest pitcher of all time, better than Pedro because he had more staying power. And I'd hold my nose and have to rank Barry Bonds as the 4th greatest player of all time, behind only Cobb, Ruth, and Williams. And I know that a great many people are perfectly content to ignore steroid use and will happily put Bonds above everyone but Ruth, and some even do that.
Regarding the era of 300+ innings and 20+ complete games, oh! how I miss the days. The high-stamina pitchers of those days were true warriors, often going 12, 13, and 14 innings deep. Spahn and Marichal went 16 innings, and this in the live-ball era! Those old pitchers had that warrior mentality that I do not see today. I greatly miss the warrior ethos that the great ones once lived by.