Theory behind B and C positions

[SanDiegoSteve]

Originally Posted by David B

I could see a veteran umpire getting away with it, but for the younger umpires, the coach is going to eat your lunch making the call from that far away.

The same reasoning applies to why you should be in C with R3. Out here, coaches will wonder why you are in B to see a pick at 3rd. They expect BU to be in C, which sets up a more natural angle to a play behind R3, plus you're a lot closer to the tag play, which is what they want to see.