But Junior WAS the de facto boss in Season 1. He had full power, Tony was just the one the capos went to complain to. The whole "official boss/front boss" arrangement with Tony started after Junior got arrested, and Tony took over his operations and ran him out of business, leaving him with just 5% of everything. The entire point of why Tony didn't want to be boss right away is so that Feds concentrate on Junior instead of him, even after Junior was in custody - it's better if the Feds think they have the Boss himself and not just a capo, though that didn't exactly work out as they quickly found out that Tony is the front boss.
At Jackie's burial, Tony says "He thinks he's the King of Kings. Truth is every decision is made by me" in front of the other Capos as well as Hesh, And then when he goes behind his uncle's back to get Johnny Sack involved in Junior's taxing of Hesh, Johnny says, "So you are still running things."
Also, when the Feds bring Junior in and try to flip him at the end of Season 1, he tells him that he was allowed to earn, and allowed the title, but he "did not make policy and was not in the New York loop."
However, to Hesh he says he doesn't want to become Boss, let Junior die of the stress, that's what gave Jackie the cancer.
