However, the "boy is growing into his man's body" and with it has come a new attitude.
Parker admitted to Barry that he didn't know what he was thinking by letting himself go physically.
"I told him that is what I had been telling him for the past six years," Barry said.
The most common observation from observers in the Parker entourage this week was how trim the fighter looked compared to recent fights. At one point during camp Parker was as light as 106kg, but his trainer expects him to be closer to 110kg by weigh-in.
"He's bigger in his arms and across his back, but he's a lot trimmer around his gut… He's watched what he ate for the very first time."
The fact Barry has not had to spend time "taking 15-20 pounds off" Parker has resulted he says in a hugely positive camp where they have worked hard on his head movements and feints, something he wants the fighter to implement more in the ring.
While he's had "sparring partners jumping at shadows" with his feints, they know translating that to a fight situation is a different story.
Truth be told, Parker is unlikely to need his full range of skills to cast aside the 39-year-old Leapai, who one boxing website described unkindly as having not beaten anybody with a pulse recently.
Parker was slated to fight the tall and rangy Eric Molina but after negotiations stalled, Leapai was called in as a late replacement.
Barry expects the Australian to try to use his strength and physicality to disrupt Parker, but said he'd be disappointed if his fighter found himself on the end of one of Leapai's overhand rights – his knockout punch.
"His best days are behind him," he said dismissively.
Parker's on the other hand, Barry was quick to point out, lie ahead.
Dylan Cleaver travelled to the US courtesy of Duco
