In Bruce Arians' book “The Quarterback Whisperer,” he says former Indianapolis Colts quarterback Andrew Luck is a natural.

He wrote:

“As if everything his father [XFL Commissioner Oliver Luck] knew about the game had been transferred to his via genetic code.” It's fair to say, he was surprised to see the 29-year-old walk away from the game of football.

During a Sunday press conference, the new Tampa Bay Buccaneers head coach said this on Luck's retirement, via TampaBay.com's Rick Stroud:

“I was watching the Florida (vs. Miami) game and I saw that and I was really in shock. I know he's been struggling with his latest injury and the last time I talked to him he was fired up about the year and the team.”

Arians scouted Luck when he was a prospect entering the 2012 NFL Draft. Then, he was his first offensive coordinator in the NFL. He's known Luck since the beginning of his career to the end of it. Arians has nothing but kind words for the now-retired man. He remains shocked, however, considering his toughness and mental fortitude.

“Knowing his toughness and his mental toughness, this does surprise me. There’s got to be something wrong somewhere. I know because he loves the game so much. I did two of their games last year (as an announcer) and he came right off the bus to come say hi and tell me about how the defense was doing, the young receivers, and how excited he was. To see it is very disheartening.”

Arians isn't the only one shocked by Luck's retirement, but his connection to Luck is deeper than others might appreciate.