The biggest bust in Yankees history was 7 feet tall, made $40 every home game and spent most of his brief career in the upper deck.

From 1979 to 1981, the Yankees employed a mascot named Dandy. He was big and blue and a spectacular failure—a historical oddity for a proud franchise that has collected 27 world championships but would just as soon forget he even existed. Which, to be fair, isn't terribly difficult to do.

"It's...