From earlier:

scullyangel Posted:

As far as I know, was is correct. The reason for the weird tiny brackets is that certain medal ranges populate a certain number of brackets. When one of the brackets in that range maxes out on bodies a new bracket automatically populates. If this happens well into the Domination week, the bracket tends to stay tiny since most Domination players get in within the first 3 days of the new round.

So yeah, pretty much luck, although you increase your chances by not getting any scoops at all until close to the end of the round. I think there might be a mechanism in place so you don’t get any medals if you’re in a one-man bracket, though.