Next basic question

Here's a good article that explains much about positioning behind the plate:

http://www.umpire.org/writers/plate1.html

That article has a lot of good info in it. The key to calling any ball / strike is tracking the pitch into the glove. That's a must. It can be hard to do this with little squirts because of a variety of reasons.

The main reason we set up in the slot is to avoid getting hit by foul balls. Outside of the slot is the kill zone. As you move further out from the slot, the velocity of the foul ball increases. Think of it as a lever action. Increase the length of a lever and you get more force.

Trevor,

you asked "why" does the umpire set up inside the batter.  I was told that the reason for this positioning is that it's the least likely spot for a batter to foul off a pitch, hence it's the safest place to be.