[Andy]

Commenting first on what actually happened, I say the BU makes the call to the best of his ability, then goes for help if needed. Awkward situation, but probably the best that can be done there.

My thinking is that this play should have been covered differently. With a runner on first and the BU in B, the PU should trail the BR down to first watching for fair/foul on the ball near the line. Once it is clear that the ball is fair and there is not going to be a play at first, the PU moves diagonally across the infield to cover any play at third base. The BU should basically remain in the B position outside the infield and be prepared for any play at first or second. By staying there, it is only a few steps to have a decent angle at either base.

I am reading your post that you were thinking that you needed to cover third base as well and movement toward third is why you ended up with the crummy position to make the call at first. Let me know if I am completely off base.