Don't know much about this topic but i think that peoples thinking on the FBI is a bit off.

If anything wouldn't the FBI say there were more chicago outfit members, just to justify having a squad dedicated to them and getting better funding. They don't get anything out of downplaying anything and saying a groups weak cause then there superiors will just turn around and say well "you don't need the money you did last year". Its like every state and small shithole town claiming they have mexican cartels operating in them just cause they had a few illegals slinging there.