On-foundation percentage actions a batter's power to get on foundation. It is calculated by getting the sum in the batter's successes in getting on foundation (hits in addition walks as well as hit by pitches) and dividing that with the batter's overall plate appearances (at bats in addition walks http://johnathanayrmd.thelateblog.com/5536901/what-is-beisbol-things-to-know-before-you-buy