Running Lane - Whose Call?

[tcarilli]

Originally Posted by Manny A

Bases loaded, infield in, and the batter hits the ball to F6. F6 throws home just slightly too late to get R3, and the PU makes an emphatic Safe call. Then F2 throws to first to make the play on the BR. BR is a few steps from first base, with his left foot outside the lane. U1 clearly sees that F3 couldn't find the throw until it gets past the BR, and F3 reacts too late to make the catch.

U1 is supposed to be silent here?

So, why can't the PU also see the RLI in this circumstance?