How late 49ers coach Bill Walsh wrote a 550-page book that became a bible for NFL coaches:

“So it was no surprise that Walsh instantly regretted retiring. Believing that he left at least one Super Bowl on the table, Walsh was ‘melancholy and terrible,’ according to Craig. That the 1989 49ers were more dominant in the playoffs under new coach George Seifert than they ever were under Walsh made it worse. Walsh hated that Seifert won a championship that year with his team, his West Coast offense, his philosophy; he so hated the ring that the team awarded him that he gave it away. ‘He didn’t want them to win,’ Craig says. ‘He couldn’t hand over the team he had created to someone else, because he wasn’t capable of it.’

“He tried broadcasting but quit in 1991. ‘I’m not going to sit for three hours and let some 27-year-old f– in my ear tell me about the game,’ he told Brian Billick, former Ravens coach and one of his many protégés. In 1992 Walsh returned to Stanford, where he had coached in the ’70s, but left after two losing seasons in three years, his magic gone. ‘He needed to be Bill Walsh,’ Billick says. ‘He needed to be a genius.’

“So he decided to write a book.”