Can you cover the distance from home to first fast enough to stay alive? 4.2 seconds is the difference between benchwarmer and starter. 4.2 seconds is the difference between being a player and being a prospect. Between you and the next level. Think about it this way: in 100 at-bats, legging out 10 more grounders hit to the left side ups your average 100 points. Thats the difference between being a .300 hitter and a .400 all-star.