Cause Brasco helped kick the Bonanno family off the Commission, which The Commission Case weakened both the Colombo and Lucchese families, the Genovese escaped that fate, but lost Salerno in the trial, The Gambino's lost Dellocroce before the trial and Castellano was killed before the trial began, thus the Gambino's had their own problems with the Genovese and Lucchese crime families after that. Also the Bonannos were excluded from taking part in any joint family operations, which law enforcement always went after cause it was easier to bust a whole group on RICO charges. No one was really going after the Bonannos, other crime families or the FBI cause they thought they put the final nail in the coffin for the Bonannos.
The Bonannos were already one of the smaller NY families before Brasco.
Bill Bonanno in Honor thy Father claimed the Bonanno's had 400 members in 1965, not exactly a small family. In 1961 the F.B.I. counted 2700 made members in the 5 New York families. That would make an average family of 540 members each at that time. Certainly some of the families had more than 500, while some had less.
Keep in mind that membership estimates prior to the 1980's are rather suspect. In hindsight, there's no way there were that many members in NY, even back in the early 1960's. According to Al D'Arco, the maximum membership for the Genovese and Gambino families was 300, the Colombos 150, and the Luccheses and Bonannos 125-140. But even if you go with the bigger estimates we've seen, it's nowhere near 2,700.
