Healy said he had expected, and hoped, England would continue their winning ways after their enthralling series win over Australia to set the stage for an epic rematch this summer.
But England's performances over the past 15 months have been anything but flattering and they have been given little hope of retaining the Ashes in Australia without their injured captain Michael Vaughan.
England have won just five of their last 13 Tests, including one by forfeit, and will arrive in Australia earlier than planned after being knocked out of the Champions Trophy in India in the pool stage.
''It's definitely not natural and I don't know whether it's been explained in England, but I can't work out why it has happened,'' Healy told Australian Associated Press.
Healy, who still holds the world record for the most test dismissals by a wicketkeeper with 395 from 119 Tests, said he was disappointed by England's lacklustre displays.
He added that England had an obligation to play better after beating Australia.
''You beat the world champs, for the good of the game you need to keep beating everyone else as well,'' he said.
''Sure have a headbutt and a battle and maybe lose to the world champs the next time, but with other opposition, you should be starting to dominate a little better than they have in the last 12 months.'' The England squad are due to arrive in Australia on Sunday morning with the first of five Tests starting at Brisbane on Nov 23.