The case for Koufax
I purposefully framed this argument in terms of who you would select to pitch an entire season for the Dodgers because the case for Koufax is built on his postseason performance.
The starter, nicknamed the Left Arm of God, won three World Series titles with the Boys in Blue, earning the MVP award in two of those victories. He was completely dominant over eight career postseason starts—remember, there was only one playoff series back then.
Koufax’s 4-3 postseason record fails to tell the story of how good he was when the games mattered most. He is one of only two pitchers (the other, Mariano Rivera) to have an ERA below 1.00 (0.95) with at least 50 playoff innings pitched. Over 57 World Series innings, the southpaw allowed only 6 earned runs, striking out 61 batters while only walking eleven. He surrendered only 36 hits.
For the near perfection Koufax is remembered during the postseason, Clayton Kershaw’s reputation is quite different. While some Dodgers fans understand there is nuance to Kershaw’s playoff record, the overall numbers still aren’t good. Comparing World Series numbers to World Series numbers, Kershaw’s 5.40 ERA makes Koufax’s 0.95 number look even smaller.
Kershaw has had to pitch in a lot more playoff games due to the layered playoff structure in modern baseball. Over 32 games, 25 of which were starts, he is 9-11 with a 4.43 ERA, 9.7 K/9, and 2.6 BB/9.
However you cut the numbers, Koufax was one of the most dominant big-game pitchers in baseball history. Kershaw, while perhaps not as bad as the numbers indicate, is far from dominant in October. With the regular season numbers exceedingly close, choosing Koufax over Kershaw for the postseason difference is a logical decision.