I've never seen a price that dropped lower than the group rate I got except once. Just after the retart, I think, Royal added Quantum to Seattle doing Alaska. This was a change that redeployed Quantum from the Asian market. We were already booked on Ovation with a pretty good price through our TA's group space. When the Quantum itineraries dropped, of course that increased supply and lowered the price of all Alaska cruises out of Seattle. Before I even realized there had been a drop my TA emailed me letting me know that there was a drop in the group rate we had already secured.
That is the only price reduction I have gotten on group space.