[Goose]

The OL pass protections are modified/called at the line and not necessarily in the huddle.  Run plays will script out a lot of the OL's behavior--I wonder if blocking assignments are ever changed for run plays (my guess is no--if the defense lines up heavy on the playside, maybe the offense ought to check out of that play).

I think you are mostly right. On running plays, the center can designate "who is who" if the defense lines up with 5 at the LOS for example. I think the linemen are expected to recognize what to do in response to where (covered, left gap, right gap) the DL lines up on them for running plays.

[Goose]

The OL pass protections are modified/called at the line and not necessarily in the huddle.  Run plays will script out a lot of the OL's behavior--I wonder if blocking assignments are ever changed for run plays (my guess is no--if the defense lines up heavy on the playside, maybe the offense ought to check out of that play).

I think you are mostly right. On running plays, the center can designate "who is who" if the defense lines up with 5 at the LOS for example. I think the linemen are expected to recognize what to do in response to where (covered, left gap, right gap) the DL lines up on them for running plays.