Here is another version, copied not mine.
WHO'S GOT THIRD (of course, WHO HAS THIRD would be grammatically correct, and WHO COVERS THIRD correct for umpires)?
The answer
isn't "I don't know"!
.................................................. ..........................
In two-person mechanics, there are SIX instances that are the BASE UMPIRE'S CALL:
1) batter-runner on a triple,
2) the last runner into third base,
3) a lone runner on fly ball advancement,
4) any return throw from the plate area, or cut-off by a player,
5) a steal or pickoff, and
6) the FIRST THROW only BY AN INFIELDER
Elaboration:
#6 means that the PLATE UMPIRE has the call at third on the "first to third" play when the runner breaks from second. It also means that with runners on first and second and a hard one hopper to left field, the plate umpire may very well have a FORCE OUT CALL at third base because that is NOT a first throw from an INFIELDER
#4 means that even though the plate umpire has moved up to the holding zone at the beginning of the play, if the throw toward home PULLS him/her back toward the plate area, the BASE UMPIRE has to take the subsequent play at third base
Pregame these coverages with your partner!
.................................................. ........................
Yes, some are redundant.

As copied, not mine.