Well, any warm body for 7 innings with Mariano Rivera for the last two over Pedro Martinez any day, especially if it is game 7 of the 2003 LCS.
Pedro was the greatest pitcher in baseball for several years for 6 innings. The Yankees just took a lot of pitches and waited for him to get tired.
They tried the same thing in 2001 in the WS against Randy Johnson and Curt Shilling but those guys didn't get tired.
Still, keeping to pitchers from my lifetime, my 1-5 would be (for a game I HAD to win):
1. Koufax
2. Gibson
3. Seaver
4. Hunter
5. Pettitte
I am not saying these are the best pitchers ever, just as Troy Aikman was not the greatest quarterback even of his era. But if I had to win a playoff game and had to choose a quarterback in that generation he'd be the guy.
Maddox and El Duque get honorable mention. I recognize that Randy Johnson, Curt Shilling, Josh Beckett and one or two others belong here, but hating their guts clouds my judgement.