Is an on-deck batter required?

[tommyleo]

Originally Posted by Rich Ives

It's in the MLBUM:

ON-DECK CIRCLE
The next batter up must be in the on-deck circle, and this is the only player who should be there (i.e., not more than one player at a time).

Very interesting! Thanks.

This rule could be read two ways. On first glance, it would seem that the rule specifically mandates the on-deck batter to be in the on-deck circle the entire time the preceding batter is at bat. But perhaps this rule is only meant to control the on-deck batter's position on the field of play if he leaves the dugout (that is, making sure he stays in a defined area when not in the dugout). I have never seen an on-deck batter penalized or even warned for leaving the on-deck circle (perhaps to grab a different bat), so it would seem that the on-deck batter has the option, but not the obligation, to stand in the on-deck circle.

Also, is there a defined penalty for an on-deck batter not being in the on-deck circle?