Swann, who retired after three Tests of the the 5-0 whitewash, was just one of a number of players who failed to get anywhere close to peak form as Australia reclaimed the urn in style.
As the on-field leader Cook shouldered much of the blame, with his captaincy dissected unfavourably by a number of observers - led by the increasingly partisan Shane Warne.
Cook was variously criticised for being too defensive, too reactive and uninspiring in comparison to opposite number Michael Clarke, but Swann feels he was hamstrung by those around him.
"He had to change things and try to be a bit funky as the series went on because we were terrible," Swann said in a special edition of BBC Radio Five Live's Not Just Cricket, featuring himself and James Anderson.
"Whatever we tried wasn't working. You can understand people saying 'he's not a good captain, Clarke's got the rub on him' but Clarke had a guy he could turn to at any point to get a wicket, seemingly at will, and Cooky never had that."
Cook is almost certain to remain in charge of the side after the England and Wales Cricket Board's new managing director Paul Downton completes his review of the Ashes.
One reason for that is a lack of credible alternatives but Swann believes not even one of England's finest leaders would have been able to alter the course of the 2013-14 series.
"No man could have captained us this winter, not a captain on earth. You could bring back Mike Brearley and it wouldn't do any good."
"We were terrible."
Swann did not exempt himself from blame, admitting he called time on his career before the end of the series because he was no longer contributing.
"Quite simply I was awful," he confessed.
"It gets to a point where you realise you're hindering the team, not helping them in any way, and it's a horrible feeling to come to terms with.
"You're playing for your country, you love playing cricket for England, it's your life. To come to that conclusion is actually one of the most sobering decisions I've ever had to make.
"It was horrendous."