player out of bounds

Question
It has been ruled by an ump that if a 1st baseman stands with one or both feet out of bounds when the pitcher delivers a pitch to the plate that the runners advance similar to what happens in a balk. True or false? If true, can you quote the rule for me  please?
Thanks for your efforts here> I love to read your stuff.

Answer
Brian,

Here's the rule:

4.03 When the ball is put in play at the start of, or during a game, all fielders other than
the catcher shall be on fair territory.

This has always been interpreted that both feet of the defensive players are in fair territory.  The penalty is the same as a balk.

Hope this helps!

Brian