Looking at this as calmly as possible...
The Wallabies aren't a bad side. This season they have beaten Wales (European champions), South Africa and Argentina. So, not too shabby. They have been whacked by New Zealand, sure. But they're the next-best team in world Rugby. That's not "sack the coach" territory.
The Wallabies have shown a lack of penetration in many of their games, and that has made them frustrating to watch. From my perspective, this is mostly because they don't have any creativity in the centres. Barnes at 12 may turn out to be an answer to this (I quite like the idea of Barnes and Ashley-Cooper in the centres), but for the most part the team has relied on centres who just crash it up. I don't blame Deans for this - with O'Connor out, what are his choices?
Cooper's form for the Wallabies this year has been poor, following the RWC last year when it was awful. No-one doubts his talent. But it's highly unattractive when a player in poor form looks to blame other people (including the coach) or the team's style of play. The team's style of play doesn't make you kick out on the full, or get charged down, or throw passes to no-one.
An ideal situation for Australia would be to have Cooper in the team, fit and confident and firing. But if he really wants to play League, let him go. I suspect his manager is in his ear telling him that this form is someone else's fault, and that he's a genius in high demand. But on current form, if he signed with the roosters, he'd be running around for Newtown at Henson Park.