It's silly to me to overreact to Green's bad game by making this move unless Green is just showing that he's not getting it. If Green had sucked since we drafted him, then I'd have been all over cutting him and replacing him. He was considered a solid tackle coming into this season, to the point that we gave him a chance to compete for the starting guard spot.
Starting a player who has never been more than a subpar tackle over one who may have had a one-game aberration is a poor way to handle this IMO. Give Green a little rope and see if he hangs himself. If he does, the backup plan needs to be kicking Martin out to tackle and putting either Bell or Green inside.