According to Wiki:
Like the double-play combination of Tinker, Evers, and Chance, Warren Spahn and Johnny Sain were linked together in verse. The poet responsible for this pairing was Gerald V. Hern, an editor of the Boston Post. In September of the 1948 season he penned an ode to the Boston Braves aces:
First we’ll use Spahn, then we’ll use Sain,
Then an off day, followed by rain.
Back will come Spahn, followed by Sain,
And followed, we hope, by two days of rain.