So I played at 70 MMR as antag. After it took around 30 minutes to find a game, the match was populated with enemies with no health, and very low spawn rates.
The map was Enemy Within, and it took longer for me to spawn in for the first time than it did for the Raiders to kill the first squid. I was still materializing while they were taking control of the point.
Squids died in seconds, and council offered no real resistance either. Once we got to phase 2, no Acolytes spawned, or if they did, they died as soon as they were shot at. Based on the attacks, I estimate they had maybe 100 or 200 health.
Even with Tolchok and outleveling the entire team (which this community seems to think will make you an unstoppable force), there was no way to win in a true 4v1 situation when the map was clear of all hostiles except me.
Not only does a difference in MMR cause the game to become too hard for the raiders if the antag is lower MMR and raiders are high, but if the antag is too high and raiders lower, the antagonist is on their own because the game overcompensates for the situation.
I won my previous game by just killing the protector on Fistful of Sand, as all antagonists know to do these days, and my MMR did not go up. But lose on Enemy Within 40 minutes later, and drop 2% MMR? The formula seems to have some issues.