I’ve just discovered that a lot of young pitchers (12-17 yr olds) leap as a result of leaning their chest or head too far forward too far into their stride. While all pitchers need some amount of lean to start the pitch, once the stride foot drives forward the pitcher straightens up her posture in order to prepare for the release. But some pitchers keep this forward lean, which only has to be slight and it’s enough to pull the back foot off the ground – resulting in a leap and an illegal pitch.
