By-the-numbers bio of a popular athlete. Bo Jackson is best known for playing two professional sports--baseball and football-and playing both superbly. According to baseball slugger George Brett, who wrote one of the two ""appreciations"" that begin this book, Bo ""could win the Indianapolis 500. . .knock out Mike Tyson. . .win the U.S. Open--golf or tennis, either one."" But veteran sportswriter Schaap (Steinbrenner!, 1982) does little to ferret out the source of Bo's athletic greatness. Instead, he offers a conventional rags-to-riches tale of a young bully from Bessemer, Ala., who grew up to smack home runs instead of his playmates. Born Vincent Jackson, Bo suffered through a poor, sometimes violent childhood. Things improved when he discovered sports, the perfect outlet for his energy and anger. A high-school track champ (""I was seventy-five percent of the team""), he went on to win the Heisman Trophy as the nation's best college football player, and then surprised his fans by choosing a career with the Kansas City Royals baseball tram, demoting foot. ball to an off-season ""hobby."" Bo comes off as a remarkable physical spec/men--several people comment on his chiseled torso--but otherwise normal, even bland. He adores Chuck Yeager (""I'd like to go fishing with him for half a day, then go up in a jet with him""), hates practical jokes, finds Reggie Jackson arrogant, ranks as his biggest thrill the day ""I watched my son being born."" Schaap tries to juice things up with third-person interludes--Bo refusing to sign autographs, Bo lying in bed with his wife--but these are glossy snapshots, nothing more. Ho-hum. Good for Bo fans, boring for everyone else. You'd do better to drop your money on a Royals ticket, and see Bo hit one of his tape-measure home runs.