Theory behind B and C positions

[chartrusepengui]

newbie question - I've watched 3 games this week. In 2 0f the 3 games - 2 person system, the BU was in C with R1 on first. We follow Fed here. This goes against what the manual says. I asked and was told that they go to C in this sit because they can turn and face first from C at the pitch. they get a "great" angle and have a slim profile to the batter/ball if hit towards them. I was also told that being a rook - I should follow the manual. Is this common?