That chart, while excellent, in no way indicates "made guys."
For instance under Tony Spilotro it lists Frank Rosenthal.
For reasons that should be obvious Rosenthal was never a made guy.
Relating back to your question as to how the Outfit could diminish so rapidly, almost everyone on that chart is dead.
For example, every single person in the top two rows of the chart is dead. Of those heading the charts below, only Lombardo is alive.
I don't recognize all of the lieutenants but all of those I recognize all except Marco D'Amico are dead, and he is not a made guy anyway, I've heard.
I can't read the soldiers names.
That particular chart was compiled by two posters over on the Real Deal forum. One of them is Scott Bernstein, who was the co-author of "Family Affair," one of the books written on the Family Secrets case. Even though the Outfit started using the traditional making ceremony since at least the 1970's, it's still harder to identify which guys are formally inducted. That chart is rather expansive in terms of who is connected to the Outfit but by no means is most of the names on it dead. Only a few are and they are listed as "deceased."
Mods should mind their own business and leave poster's profile signatures alone.
