However, the second-year mentor says it's understandable given Swan's remarkable achievements over the previous four years.
And the Magpies boss says the premiership star has given every indication he is back to his most driven.
"Even the most professional disciplined players ebb and flow," Buckley told AAP.
"Swanny had an ebb.
"It was probably about time, given the three years prior he won three Copeland Trophies (as Collingwood's best and fairest from 2008-10) and a Brownlow (in 2011).
"In the last four years, he's one of the most consistent players to ever play the game.
"When I say that I reckon there's an extra couple of per cent in him, it's not saying that he hasn't been a great performer and a very consistent performer.
"That's just a coach asking for a little bit more and I ask that from all of the players."
Swan was suspended by the club late last season for an alcohol-related disciplinary breach.
But Buckley said while Swan made a very poor decision, he wasn't the only player who needed to fractionally lift their commitment from last year.
He said Swan's lapses attracted more public attention than others.
Buckley said while the midfielder was a "different character" who wasn't solely focused on football, he took enormous pride in his performance.
"If he can't have the influence on games that he wants to, he identifies that pretty quickly," he said.
"He came back with a real hunger to have a great pre-season.
"He's been able to do that.
"I think you'll see, as the season progresses, I think you'll see a really hungry footballer who'll find that extra couple of per cent this year compared to last and who has the drive to want to play and influence it as much as he can."
