They weren't really necessarily from the same crew though. The Cicero crew is an entity unto itself, in that it is composed of two separate factions: The Carlisi/Marcello Crew & the Ferriola/Infelise Crew. These two factions became even more separated & distant following the incarcerations of their upper echelon members. This became evident when the Ferriola/Infelise faction (DeLaurentis, Inendino, Marino, Sarno) knocked down Big Tony Chiaramonti & Little Tony Zizzo. (Carlisi/Marcello crew members), and in doing so, claimed the entire Cicero/Berwyn/Melrose Park territory for themselves. Prior to this taking place, there were two "bosses" of Cicero. Mike Sarno, who was acting on behalf of his superiors who were incarcerated at the time, and Little Tony Zizzo, who was acting boss on behalf of Jimmy Marcello while he was imprisoned. They were 100% equals.

Mike Sarno was a member of the Rocky Infelise crew. He worked under a guy named Bobby Salerno, who worked under a guy named Lou Marino, who worked under a guy by the name of Solly DeLaurentis. So yeah, it's quite obvious that he was just holding down the fort until Jimmy I & Solly D got home.

People get confused because the Cicero crew is the only Outfit family large enough that it had to be split up into two factions to cover the territory. This isn't the case with any of the other crews, which operate under one boss/panel.

You have to disregard a lot of what the feds put out there for the public. The feds largely go off of information they obtain via low level informants. These informants aren't privy to high level information/hierarchies.

Hope that helps clear some stuff up regarding Mike Sarnos place within the Outfit.