The idea occurred to him as he was moving into middle age and realized he would not be able to continue doing all the athletic stunts the Phanatic specialized in, especially in what had become almost a daily job — what with games, events and parties that contracted the Phanatic. He realized that the mascot business, spurred by the success of the Phanatic and other early professional sports mascots, like the San Diego Chicken, was starting to boom, so he left the Phillies and his big green animal suit and started consulting, teaching moves and designing costumes.

“It’s been a wonderful business, and I get to show people how to have fun, which is what my first boss told me to do in the first place,” he said.

That boss was Bill Giles, then the general manager of the Phillies. Mr. Raymond — whose father, Harold R. Raymond, known as Tubby, was the longtime football coach at the University of Delaware — had a summer internship with the Phillies, in part arranged by his father, a friend of Mr. Giles. David Raymond loved the work and wanted to continue his internship the next year while earning a few credits for graduation from Delaware.

“I got a call and just assumed they were going to say, ‘Sorry, someone else is getting it this year,’ ” said Mr. Raymond, whose dream had always been to be a sports coach like his father.

Then Mr. Giles asked if he could make a commitment to come to every Phillies home game. Mr. Giles had contracted a designer who used to work on the Muppets to come up with a costume. The Phillies had just won two division titles, but they still were not drawing young fans, and Mr. Giles thought a young man like Mr. Raymond dressed like a big green fictional animal would do the trick.

“I didn’t actually wear the Phanatic costume until the first night I went on the field,” said Mr. Raymond. “I asked Mr. Giles what I should do. He just said, ‘I want you to go have fun.’ His idea was that if I had fun, then the fans would, too.”