[Rich]

Originally posted by DownTownTonyBrown
Here's what I found....

Under Game Situations
(15)RUNDOWNS. The best coverage for rundowns is by both umpires, one at each end of the play. When the situation allows both umpires to work a rundown, talk with your partner to let him know what you are covering. The call should be made by the umpire toward whom the runner is coming. This shows good teamwork and looks good to everyone.

My original answer was assuming a rundown situation.

Without the rundown, after the first runner had scored and I (PU) saw an impending play at third, I would be moving toward the library (the waiting area in foul territory, 2/3, or more, of the way to 3rd). Subsequent play near 3rd would be my call and your partner, as he said, should be watching the other runner.

All of this is irrelevant, because the situation does not allow both umpires to work the rundown. The BU is responsible for the BR. What if there is a snap throw to second -- should the base umpire guess at that call from the vicinity of third base just so he can "help" with the rundown?