John McVay knew his grandson, Sean, was serious about coaching when as a youngster he would fall asleep reading Bill Walsh’s book: “Building a Champion: On Football and the Making of the 49ers.” It was published in 1990.
“It’s a game plan for anybody who wants to be in this business,” the elder McVay told The Post by telephone from his home near Sacramento, Calif. “Sean would always be reading it, and then he would tell you, ‘I read this and that and the other.’ He would read a few pages at night until he fell asleep. You could tell he had a deep interest in it.