France beat Scotland and Italy in the Six Nations but were thrashed by England and Ireland, and their second-half collapse against Wales showed their mental fragility.
Brunel, who has lost 11 of his 15 tests in charge, admitted that results had not been good enough but he is confident that three months of preparation will put France, currently eighth in the World Rugby rankings, back in the mix for the World Cup.
They will face Argentina, Tonga, England and the United States in the Pool phase in the Sept. 20-Nov. 2 tournament in Japan.
“I’ve been saying this from the beginning: the World Cup is something totally different,” he said after France laboured to a 25-14 win in Rome on Saturday.
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“History showed it many times: regardless of the circumstances of the Six Nations, the World Cup is a special event and we will prepare accordingly.
“We will do some fine-tuning on the areas where we were not good.”
France's performances, however, suggested that fine-tuning would not be enough to reach the knockout phase of the World Cup.
Even though flyhalf Romain Ntamack started the last three games with scrumhalf Antoine Dupont, France need to erase years of inconsistency at halfback and change is unlikely to happen in a few months.
Ntamack, however, was one of the few bright spots for France in the Six Nations, with his vision and quick decision making helping ease the pressure on an otherwise very ordinary team.
"I have learned a lot, I have improved playing with and against the best," the 19-year-old said.
Some players criticised the management after a 44-8 rout at the hands of England, and scrumhalf Morgan Parra and Camille Lopez were dropped from the squad.
Lopez was recalled for the final match but did not hide his frustration when he was called on to play for only four seconds during stoppage time against Italy.
While it would usually be a routine win for France, in the light of their recent performances, prevailing at the Stadio Olimpico was a relief.
"We are essentially relieved, to be honest. We are happy, but most of all relieved. We were really scared," said Felix Lambey.
Mathieu Bastareaud even admitted that France, who again appeared to play without a coherent game plan, were fortunate to beat Italy.
"We got away with it, we were lucky," the burly centre said.
"We were nervous because we knew that losing this game would be making a lot of damage," said winger Yoann Huget.
A defeat could have put Brunel's job on the line.
Instead, the coach is highly likely to lead France to the World Cup, although French media report that former international scrumhalf and ex Stade Francais, Montpellier and Toulon coach Fabien Galthie could be hired to bolster the backroom staff.
(Reporting by Julien Pretot; Editing by Toby Davis)
