Obstruction - what's your mechanic?

[Atl Blue]

Dave:

I think you are correct, but I don't think that is in conflict with J/R. J/R simply says when you see OBS, call it and decide to where you are protecting the runner. As the play unfolds, you may change that decision with "post OBS evidence".

I think this is the thought process we all go through if calling the play properly. As soon as we see OBS, we don't say, "OK, now let's wait and see where this goes.". We make an initial interpretation such as "That OBS cost him two steps. I have him to 2B and if he is out by less than two steps, he gets the base." But then you see the ball get by F9, you certainly can change your mind, still thinking it was a "two step OBS", except those two steps are steps into 3B.

I don't think the PBUC and J/R are at odds. I think they are using different words to get to basically the same place: see OBS, call OBS, make an intitial determination on the severity of OBS and therefore the protected base, and change it if the play changes.