“He’s got a plan,” Rosen said. “He knows what’s going on. He gave those guys a chance, and they couldn’t do it. He’s brave enough to start from scratch, which you never see guys in New York do.”

Rosen and Jackson met for the first time at a party in Jackson’s loft in Manhattan above an auto repair shop late in the 1972-73 season. Rosen was a writer; Jackson was in his sixth season with the Knicks, who were on their way to winning their second N.B.A. championship. The Knicks played the 76ers seven times that season, winning six of the games, including a 139-91 rout in November. But when the teams played in mid-February, the 76ers were in the midst of a two-week renaissance, winning five of seven, including an easy 114-98 victory against the Knicks.

In “Perfectly Awful,” Jackson said, “We had beaten them fairly easily the night before, so we all were goofing around in the locker room before the game and were not prepared to play hard.”

Still, the Knicks were, after that loss, 48-17, and the 76ers were 7-59 — a record that would be matched by the Charlotte Bobcats in the 66-game, lockout-shortened 2011-12 season.

Rosen’s and Jackson’s professional trajectories have converged and diverged. Rosen, a Hunter College star, medieval scholar and novelist, became Jackson’s assistant coach with the Albany Patroons of the Continental Basketball Association. Rosen coached four C.B.A. teams, while Jackson turned an assistant’s job with the Chicago Bulls into 11 championships as the head coach of the Bulls and the Los Angeles Lakers. Jackson never offered Rosen an assistant’s job, but rumors that he was a candidate at one point were scotched when Bulls General Manager Jerry Krause called Rosen and said he had other plans.

Rosen said he told Jackson: “Why didn’t you call? We’re friends, and you sent this guy to call me.”

Rosen said they didn’t speak for eight or nine months.

Rosen, who turns 74 on Sunday, works as a columnist, mostly for digital sites like HoopsHype, while writing fiction and nonfiction books about basketball and baseball.