The Moneyball approach only works if your scouting system is up to snuff, in either sport. And even then, in baseball, it's an approach typically only really used by ball clubs with small payrolls as a means to stay competitive, and maybe hit stride at the right time and win the title. The major difference being is if it fails in football, you're relegated. So in football, playing Moneyball, is a very dangerous roll of the dice.