So you think it's more likely that two OCs in a row with elite rushing attacks chose to abandon them in the playoffs, rather than Lamar calling his own plays (or at least having great influence over them) and trying to play superhero with his arm?
I never got the impression that Lamar had any input into play calling under Roman. This year, sure, he seems to have had a good deal of input, but I don't think he was routinely calling the plays and never heard or read anything suggesting that, so I don't know why that would be likely.
In any event, if the QB is calling the plays, and the coaches don't agree with what's happening, then they can and should take back the play calling responsibility. If Lamar was calling plays the staff tacitly agreed with his the play calling or they'd have put a stop to it. More likely IMO it was just the normal situation where the OC was calling the plays.