Don said:
Guess I needed to be there or something. Looking at stats alone yeah he was awesome but wouldn't say that stretch was the greatest ever for a pitcher.
He had what looks like 4 awesome years. 1963-1966: where he won 3 CY's.
But I'd say that I've seen several pitchers have just as good stretches for a 4 yr period:
Pedro from 1997-2000
The Big Unit from 1999-2002
Maddux from 1992-1995
just to name a few.
Here's a few stats. I haven't looked up the stats from the admittedly excellent pitchers you've listed, but I'd be surprised if they stack up overall. The closest, I imagine overall would be Maddux as I know he had some awesome years. (Just so I didn't put my foot in my mouth I did look up some of his stats, including his best 4 year stretch.) I'm not going to bother looking up the other 2 since aside from Unit's strikeouts I don't think they're close. Here goes.
Koufax:
1963:25-5, 20 complete games, 11 shutouts, 311 innings pitched, 306 strikeouts, 1.88 ERA(52% of the league average)
1964:19-5, 15CG, 7 Sh.O., 223 IP, 223SO, 1.74 ERA(49% of league average)
1965: 26-8, 27CG, 8 Sh.O, 335 IP, 382SO, 2.04 ERA (60% of league ave.)
1966: 27-9, 27CG, 5Sh.O, 323 IP, 317 SO, 1.73 ERA (50% of league ave.)
Koufax had to retire after that year because of arm troubles, so he obviously put up those '66 stats when he was much less than 100%. He was in too much pain.
Overall for those 4 years:
W-L 97-27 (.782 winning percentage), 89 complete games, 30 shutouts, 1192 innings, 1228 strikeouts, ERA 1.86
Maddux:
Best 4 year stretch 1992-95
W-L 75-29 (.721 winning percentage),37 complete games, 11 shutouts, 946 innings, 733 strikeouts, 1.98 ERA. The only place where Maddux was clearly ahead was his ERA in '94 and '95 which was around 1.60 both years.
Obviously some of Koufax's stats are higher because of pitching more innings but he still comes out ahead in winning percentage and ERA. It could be argued that pitching that many more innings could have tired him out resulting in some worse stats like giving up more runs in later innings.
I'm not sure what other stats you can come up with to show Maddux or the other 2 (who weren't as dominating as Maddux except for Unit's strikeouts) ever had a stretch of overall stats even close to Koufax's.
The shame is that if Koufax was coddled the way today's pitchers are, and with more modern medical treatments he would have had a longer career and much better career stats.