If I remember correctly, that was actually Bautista's idea when the team was in a slump. The manager decided to give it a try, and the team started winning so Bautista saw quite a few games batting leadoff.
That's really cool! Honestly, it seemed really weird to me at first, but I guess if you don't have a tradional leadoff type guy, putting someone who gets on a base a lot is the next best thing, and Bautista certainly walks a lot.