Moon, 44, never played on a Super Bowl team _ his biggest disappointment in an odyssey that spanned two countries and five franchises.
Moon's playing career will end Sunday, perhaps without him even getting into the game. The man known for his quick release and beautiful tight spirals will be the third-string quarterback for the Kansas City Chiefs against the Falcons at Atlanta.
"At every stage, people had doubts about whether I could play, and I've had to prove them wrong," he said. "I wasn't even invited to the (NFL scouting) combine (and) no one gave me an individual workout to see if I had the arm strength or whatever it was they said I was lacking. So I took the best opportunity I had in the CFL.
"I'm disappointed I never got to play in the Super Bowl. But I have no regrets about anything in my career. I think I've handled things well."
He's hardly played the past two years after signing to be Elvis Grbac's backup. But the record book will show that in the history of the NFL, only Dan Marino (61,361) and John Elway (51,475) have thrown for more yards than Moon's 49,325. His 291 NFL touchdowns rank fourth behind Marino, Elway and Fran Tarkenton.
Add his six years in the CFL, where he led Edmonton to five league championships, and Moon is the most productive passer in professional football history with 435 touchdowns and more than 70,000 yards.
"I've been thinking about it all week," he said of his final game. "I think as I walk off the field Sunday is when it will hit me."
An articulate speaker, Moon likely will have opportunities in television and radio. He might also become an investor in an NFL franchise.
He could become associated with the new team in Houston, where he went in 1984, accompanied by his CFL coach Hugh Campbell, to the NFL.
The Oilers lost their first 10 games that year and Moon took a lot of the blame. He then became one of Houston's most popular players after the Oilers reached the playoffs seven straight years beginning in 1987.
From there he went to Minnesota for three years, then came two years in Seattle before his final two years with the Chiefs.
When the time comes to bring the grandkids around the fire and talk about the old days, grandpa will have much to say.
On a cold, overcast day in Kansas City in 1990, he experienced one of the greatest NFL games, throwing for 527 yards in Houston's 23-7 victory over the Chiefs, coming within 27 yards of the league record Bob Waterfield set in 1951.
"It was just one of those rare days when everything you do is right," Moon said. "I seemed to put the ball in the perfect spot with every throw.
"But," he added with a grin, "that was many moons ago."
Two years later, he endured a terribly disappointing loss. The Oilers were beating Buffalo 35-3 in a wild card playoff game, but the Bills rallied and won 41-38 in the biggest comeback in NFL history.
"It was unbelievable," Moon said.
His greatest thrill?
A tie, between leading Washington to a Rose Bowl victory over Michigan and quarterbacking the Oilers to their first playoff victory since 1979.
Another tie, between Mike Haynes and Charles Woodson.
Last man he'd want to be sacked by again?
About a half-dozen young black quarterbacks in the league have a chance of being in the Super Bowl next month _ and many have sought out Moon to thank him for showing the way.
Tampa Bay took Doug Williams of Grambling in the first round of the NFL draft in 1978, the year Moon graduated from Washington. Much skepticism remained, especially regarding black quarterbacks who scrambled and threw on the run, like Moon.
"I think I had a hand in the change," said Moon, who spent the first six years of his pro career in Canada.
"I only feel that way because those guys have told me that. It's good to know I can take a little credit for that. You're seeing the emergence of the black quarterback today because teams want a more athletic guy who can move around against zone blitzes and the speed of defensive guys."