discarded baseballs

Question
why does an umpire discard a pitched ball that hits the dirt but not a batted ball that hits the dirt?

Answer
Freddy,

It is up to the umpire to decide when to throw out a ball.  Watch the game a little more closely - almost never is the same ball used once a bat contacts it.

The rule is that the umpire must throw out a ball when it is dirty or scuffed.  They used to let balls stay in play longer, but now most umpires throw out the ball as soon as it touches the ground or the bat.

Hope this helps!

Brian