My team had a big race last week and didn't do well. We do well in the smaller races. There was a race with several heats and there were top ranked teams in the state that we beat in the merge but when we race in big races with a lot of people we dont do well.
Define 'not well': are they slower than usual? Do they get beaten by teams they previously beat (without performing worse)?
You could be losing because of a lack of depth (non-deep teams do worse in bigger races).
Or, your runners like to start slowly in races, so in big races they get locked in by fly-and-die runners, don't get good position, and aren't able to run at their own pace because of the crowded paths.