coverage
 

r1 on second...i'm pu...pop up to f3...catch made called b/r out...throw to f5...who's call...bu or pu...what say you

bu

bu....what else is he/she gonna do? ;)

Depends for me, what call you mean:
The call on base 3 is for BU, the call for an early left 2nd-base is i.m.h.o. for PU...

The catch is PU. Everything involving R1 belongs to BU

Not trying to be cute or anything, but... Is that a Dutch mechanic? ASA gives the tag-up responsibility for a lone runner on 2B to the BU. The only time the PU has tag-up responsibilities for a runner on 2B is if there is a runner on 1B.

Don't know if it's only in Holland that way, however PU has the catch and the runner in one view. So that way it's PU's responsebility.
A catch by F7 with R1 on 1st leaves R1 for BU; a runner at 3rth with a catch by F7 gives the runner again to PU.
We let the positions of the catch and the runner(s) on the base(s) dictate us who has which runner. Catch is always for PU and the runner(s) in the straight line of view to the catch. The other runner(s) is/are for BU...

It's difficult for new bees, but if you're (a little) experienced easy.

Well, in the OP the ball was to F3 and the runner on 2B. While there is no doubt the PU could possibly catch sight of R1, the BU has nothing to do but position himself in a spot to see both and a few steps from covering 3B if necessary. The BU does not have to worry about fair/foul, possibly look around an advancing BR, F1 coming over to cover 1B.

I understand the "line of sight" point to which you are referring, but you also noted that it isn't that easy for newer umpires and maybe not for some lazier veterans. What you are noting are permissible deviations from the standard mechanic.

And those deviations turned to be our standard:rolleyes: