Who was the youngest pitcher to pitch in a postseason game?

At 19 years and 20 days, the Boston Red Sox Ken Brett was the youngest pitcher to ever pitch in a postseason game. Pitching in Game Four of the 1967 World Series, Brett picked up one strikeout while walking one.

Ken Brett also holds the record for most consecutive games hitting a home run by a pitcher. Brett slugged home runs on June 9, 13, 18, and 23 in 1973, to set the record at four consecutive games.