However, ACT Brumbies coach Fisher believes 32-year-old Gregan is still the man to lead Australia in 2007, as well as being a key player in the province's Super 14 plans for next season and beyond.
Fisher feels criticism of Gregan has been unfair, despite a Tri-Nations tournament which saw Australia finish without a win, and having lost their last five Tests, after a promising start to the winter campaign.
"Attacking George seems to be an annual event and I don't think his form this year warranted the criticism he has received," Fisher told the Sydney Morning Herald's Rugby Heaven website.
"His form has been consistent all year, as it has been for the last four, five, six, seven years, but people expect more of him.
"I think sometimes they expect too much of him, they expect him to do it all.
"All of a sudden, people seem to expect George to play a different style of play, to be a different type of player to the one he has been for the last 100 Tests.
"He's not a 95-kilogram player like (New Zealand's) Piri Weepu, who is going to take on the line all the time.
"He is still playing very well and I would expect that to continue to the World Cup."
Fisher, who took over as the Brumbies' head coach last season, said Australia's forwards had to accept some of the blame for the disappointing end to the term.
"The forwards did struggle and as a result George did not have a lot to work with," Fisher added.
"They struggled to compete at the breakdown against both South Africa and New Zealand and that is going to make life tough for any halfback."
Fisher expects the Wallabies to bounce back on their November tour of Europe, which includes Tests against France, England, Ireland and Wales.
And he remains optimistic that national coach Eddie Jones will include Gregan in his 45-man train-on squad for the tour which is expected to be named on Wednesday.
Some critics have called for scrum-half Gregan to end his 114-Test career but Fisher is confident he can deal with the pressure.
"George Gregan is a wonderful player and a tremendous leader. He is used to all the criticism so it doesn't affect him," he added.
Fisher expects both Gregan and his club and country halves partner, Stephen Larkham, who has begun weights training after shoulder surgery, to be ready for the Brumbies' opening Super 14 game against the Western Force, in Perth, in late February.