After retiring from baseball, Casey claimed to be the "Casey" about whom Ernest L. Thayer wrote his famous poem, "Casey at the Bat", which had first been published in 1888 by a San Francisco newspaper. Casey claimed that the poem was based on an August 1887 game in which he played for Philadelphia. He asserted that he had hit a "lucky" home run against Boston a week earlier and that Philadelphia trailed, 4-3, when he came to bat and struck out.