What is the call?

Dead ball, runner go back to where they were coming from.

Return what runners and return them to what base? Time of Pitch base or the last base legally occupied at the time the interference occurred? 

I'm going to go by NFHS rulings...Sec 21 Art 1 Part A... "which interferes with, obstructs, impedes, hinders, or confuses any fielder attempting to make a play..."

 

So by that wording who is atempting to make a play in this situation? In my opinion it is the catcher. Does the runner behind the plate interfere with, obstruct, impede, hinder, or confuse the catcher from making a play here? Again in my opinion, No. I have nothing here and it is a live ball because R1 did not make an attempt to interfere with the play. You need to remember that only 1 fielder at a time can be protected by this rule as only one fielder can be making a play at a time. Also remember that a runner can't immediately disappear after touching the plate. As long as there is no intentional action by R1 to interfere i would have nothing.

 

Agree 100% with coach.  It's nothing and play on.

Thanks for the input... now add a twist... what if the pitcher is backing up and is behind the first runner.  Does that change anyone's mind?

Nope... look at my above post. Only one player can be protected at a time.

 

Nope. That's on a batted ball. The distinction between protected and unprotected fielders do not exist on thrown balls.

You're right... my apologies. Still doesn't change how I would rule in this situation.

One that's had some heated discussion especially from me

.

Can't give you a yes or no on the OP. But will say a non base runner could very easily put themselves in a position to unintentionally interfere.  Other runners and the pitcher backing up is a good example in the OP. 

What if the throw popped up in the air and BR missed HP with an ensuing scramble between F2 and R? 

 

How about R1 0 outs.  B hits a flare into short RC, R1 has left early and is scrambling back. BR rounds !B sees F9 make a diving snag on the fly ball, in disgust he turns towards his dugout and pouts with hands on knees or stands and waves R1 to slide either way F9's throw hits him and..? 

 

In other words coaches, don't tell your players hey as long as you are signaling

a runner you don't have to worry about a thrown ball. IMHO. 

 

I'll be back coaching a LL major team this year, that'll give me an, interrupted a couple times, 20th year, come on sun shine..

.   

JJK I'm going to give my thoughts on it when I get off of work so I can quote the different parts I want to hit.

What if the throw popped up in the air and BR missed HP with an ensuing scramble between F2 and R? 

It depends... Who is he trying to make a play on?

 

How about R1 0 outs.  B hits a flare into short RC, R1 has left early and is scrambling back. BR rounds !B sees F9 make a diving snag on the fly ball, in disgust he turns towards his dugout and pouts with hands on knees or stands and waves R1 to slide either way F9's throw hits him and..?

 

Where is the BR? Between F9 and F3 or behind F3 in foul territory? There are many details that you are leaving out here. Just because a runner scores or is put out doesn't mean that they can immediately disappear from the field of play.