In 1968, Denny McLain won 31 games for the Detroit Tigers – the first pitcher since 1934 to win 30, and the last to do so. He won 24 in 1969, and appeared in his third All-Star Game. He was 25 years old, had just completed consecutive Cy Young seasons, and boasted a career record of 114-57. He was enormously popular, flew planes, played the organ in Vegas gigs and on records, and was married to the daughter of Hall of Famer Lou Boudreau. His future prospects seemed unlimited, until Sports Illustrated published its February 23, 1970 issue featuring McLain's face and the headline BASEBALL'S BIG SCANDAL: Denny McLain and the Mob.

The story alleged that McLain had invested in a bookmaking operation in 1967, and when it went sour and he owed money to mobsters, one of them stomped on McLain's toes, dislocating them. McLain did injure his foot late in the '67 season, but explained that he had stubbed his toes after his foot fell asleep while he was watching television – no, wait, he'd kicked the water cooler… or had he hurt it chasing raccoons?

McLain acknowledged his investment in the illegal book, and Bowie Kuhn suspended him for the first half of the 1970 season. When he returned, he had lost all his effectiveness as a pitcher; in his three remaining years in the majors, he went 17-34 with a 4.78 ERA. Since the end of his playing days, McLain has done time in prison twice: in 1985 he was convicted of racketeering and loan-sharking, conspiracy, extortion, and possession of cocaine with intent to distribute, drawing a 23-year sentence, serving a little over two years before the conviction was overturned and remanded for retrial. In 1996, McLain was convicted of embezzlement, mail fraud, and conspiracy in the theft of $2.5 million from the employees' pension fund of a packing company he had purchased with other investors. He spent six years in prison, and proclaims he had no idea what his partners were up to.

His 2007 autobiography was entitled I Told You I Wasn't Perfect.