no throw interference
 

We often say a throw is required for interference on a play like that below.
Is the physical contact the difference, or the "arm is up", or is that not really a basis for a call?

"Play: R1 on second base, no outs. B2 at bat with a 3 ball no strike count. The pitch to B2 is in the dirt and F2 did not field it cleanly. The Plate Umpire gave a verbal ball four. The ball rolls out in front of the batter's box about four feet. The batter steps out of the box and turns to discard their bat, and then turns to go to 1B. F2 now has the ball and is positioning herself to throw (arm is up) to F5 in an attempt to retire R1 stealing third when B2 runs into F2. No throw was made. Is this interference?

Ruling: Yes, even though the B2 was awarded first base on the walk, B2 is out for interference for hindering F3’s attempt to throw the ball. (Rule 1 Interference, Rule 8, Section 2F2)"

Does an umpire have time to count the steps of the throw, or is it one fluid motion where the arm is coming forward almost as soon as you realize the catcher cocked it?

IMO if the catcher stops in such a position, I'd have to take into consideration whether she actually had a play to retire the runner or was just going through the motions like a good little catcher should

I believe I have read some plays that indicate the runner or batter-runner (depending on the situation) should be called out if the runner has not yet reached the base where the play was - not whether you believe the runner would have been out.