Rule Trivia
 

R1 on first, no outs. Batter hits to left field. R1 rounds second large, but decides not to go. BR doesn't see R1 return and is also heading for 2nd.

R1 is obstructed by the SS returning to the base. Throw comes into 2nd base ahead of R1 (or R2 for that matter), R1 takes 3 steps toward 3rd, ball is thrown to F5. As the ball is thrown, BR continues to 2nd base. R1 returns toward 2nd, BR stays there. F5 throws to F4 as R1 slides in safely. F4 then tags BR.

Ruling?

BR is out, R1 was entitled to the base. R1 is at risk to be put out between the bases obstructed (if she leaves second) as there has been a play on another runner and she reached the base she would have reached if not for the obstruction.

So ... just one opinion here so far? Really?

Well
 

Once an obstructed runner is played on by the defense the ball becomes dead. At that point you then award bases. The way I read the OP R1 was played on sliding back in to 2B before a play was made on BR. At that point, the ball becomse dead.

I get the sense that you are posing a conundrum about who is entitled to the base. Should be first to acquire and not forced. So,
a.) did R1 "acquire" 2B by rounding and returning?
b.) Or does BR "acquire" by being already on the base when R1 returns?

I go with "a" and the previous posts, BR is OUT.

I thought it was retired.

Ball isnt dead unless the obstructed runner is put out prior to reaching the base they would have reached absent the obstruction. A play was made on the obstructed runner, but she was safe diving back into 2nd. BR was then tagged while also on 2nd. I also have the BR out, based on the description in the OP the runner was obstructed returning to 2nd and she was safe, no dead ball, no base awards.

It is.

What about the fact that when the play is over we are to announce the obstruction and award the runnerS (plural) the bases they would have achieved had there been no obstruction.

Had there been no obstruction on the runner, she would have made it back to 2nd before the BR got anywhere near there. We cannot and should not assume BR would have been put out - it's much more likely she simply returns to first.

Ahhhh...there is the real question.

When I read the OP, it seemed pretty straightforward that the BR would be out, so I was looking for what the "real" question was.

Since the obstruction rule says that we can award bases to the obstructed runner and any other runners affected by the obstruction, do we consider the B/R as "affected" and place her back on first?

Re-create the play, absent the obstruction. As I read it, BR would still be on 2nd without paying attention to R1, the only difference is R1 may or may not have been safe back into 2nd on the initial throw behind her; or maybe gets out of the rundown quicker.

In what way was the BR affected? Poor baserunning put her in jeopardy, not the obstruction on R1. If R1 is legally put out (absent obstruction), BR is safe. If R1 gets back safely, with or without obstruction, BR is out when tagged.

I agree...I was just trying to state the unasked question that I think was the point of the OP.

After thinking about this play a little longer, I came to the conclusion that R1 started this whole thing by "rounding large" and getting herself in a rundown. She was (potentially) bailed out of the rundown by the obstruction, but if she had not made such a large round of second, it's probable there is no rundown and B/R stays at first.

I suppose, then, that what this one really comes down to is - in the umpire's judgement was BR so oblivious that she would have continued to run toward 2nd - or was the majority of the run to 2nd due to the run-down in front of her. I guess the way I worded it and absent more information regarding BR and umpire's perception of her actions, this one could go either way.

Honestly, I don't see how either oblivious, or intentional, it was for BR to continue to 2B, would be a factor in the ruling. (oh and don't forget the 1B coach in the oblivious category).

What I may have missed in the OP was the results of the OBS.
Would R1 have reached 3B without the OBS?

While I could see an entertaining discussion arising out of that, but even if yes, I would still have R1 out. The smarter play would have been for R1 to get tagged out off the base, then we have Dead Ball, award R1 to 3B and nobody would have tagged BR.

Why because BR was tagged out which ended the play. R1 would then be awarded 3B, the the out on BR would still stand.

I don't think that's what's meant. What we're asked to do is not piece the play together completely as if there had been no obstruction but to determine who did something different because of the obstruction.
In this play, R1 is going to be back at second safely absent the obstruction as determined at the time of the obstruction. Therefore, BR is not going to get second absent the obstruction. If R1, realizing she has been obstructed decides to try for 3rd, the BR may decide to advance to second. But she is certainly not protected in doing so despite the fact that absent the obstruction she does not attempt to take the base.
Now, it's likely instructive to consider a case where the runner being obstructed clearly does make a difference to BR.
R1 is obstructed coming around second on an obvious double to left field. Realizing she can't make third now and unaware the umpire saw the obstruction she returns to second causing the BR to return to first. After the play award both runners an extra base.
Is your case more like my second or my like the first? I'd say more like the first. Yes, had R1 not been obstructed it is possible that BR would not have made the same baserunning mistake, but it's too much of a stretch for me.

I hear you. I think it's in between, and I can see an umpire ruling either way. We don't ever hold the baserunner accountable for knowing OBS was ruled. It's entirely possible BR rounded, and was going to return, but upon seeing R1 heading for 3rd advanced to 2nd ... and then when R1 started returning decided they couldn't make it back to first and stayed to avoid being doubled up.

I guess it's on the umpire here to decide of BR simply made a mistake, or took 2nd based on actions that never would have occurred without the obstruction.

I don't think that's quite right. Suppose that R1 had made it safely to third and the BR had been tagged just shy of second. Certainly, she wouldn't have gone to second but for the obstruction. But that doesn't mean the obstruction protects her. Or do you think that could also result in BR being sent back to first as well?
If you don't, then I'm not completely sure what differentiates these two.
If you do, then are you going to kill the ball when the BR is put out at second?

IMO, people are overthinking this. This is a no brainer.

R1 ELECTED not to advance toward 3B and was not obstructed attempting to advance toward 3B. Awarding R1 anything other than 2B is not justified. Really don't care how many steps she takes toward anywhere, R1 owns 2B.

R1 was not put out, so there is no reason to kill the ball until all other play is complete

I don't think we need to always take into account what other runners subsequently do that they might not have done had there been no obstruction.

Suppose you started with R1 at third and R2 at second, and R2 is obstructed by F4 as she tries to go back to second on a pickoff from F2. She gets into a rundown, and in the process, R1 decides to go home as R2 safely slides under the tag going back to second. R1 is then thrown out at home. We wouldn't rule that R1 should go back to third base because, minus the obstruction, she likely would have never attempted to advance home.

I see your OP play similarly.

IN THE OP,
- there is no reason to think R1 should be awarded 3rd
- there is no reason to think BR/R2 would have made it back to 1st
- there is no reason to think BR/R2 was affected by the OBS

As in the first response, R1 is safe, BR/R2 is out, next batter.

Yes.. the smart play would be for R1 to not touch 2B and get tagged between 2B and 3B. The defense could tag B2 on 2B all they want and it's not an out unless R1 is also touching the base exercising her right to the base.

So if they tag B2 while she is only one on 2B then tag R1 while she is off the base between 2B and 3B the ball is dead and we award R1 2B. Since B2 is on 2B she is also affected by the OBS and goes back to 1B.

Well... I guess I'm glad I posted this. I hear you all, and now agree with you. Thanks!