Ross Brawn believes that mid-season changes in Mercedes' Formula 1 aerodynamic department were the root cause of the team's slump in form during the second half of 2012.
Mercedes, which took over the world champion Brawn squad in late 2009, scored its first F1 race win as a constructor since 1955 when Nico Rosberg dominated the Chinese Grand Prix from pole position.
By the halfway point of 2012, Rosberg lay sixth in the championshp, only 34 points behind Red Bull's Sebastian Vettel. But the squad's form suffered during the second half of the year, Rosberg eventually trailing world champion Vettel by 189 points and Michael Schumacher's sixth place in Brazil its only points finish from the final six grands prix.
Team principal Brawn said that the departure of head of aerodynamics Loic Bigois, coupled with a change in wind tunnel philosophy while the team experimented with Coanda exhausts and double DRS, also played a major influence.
Brawn said: "We made a decision to change the structure of the aero group. We had to wait for [new aero chief] Mike Elliot to join us because we had a notice period he had to fulfill at Lotus.We concluded the situation with Loic and there was a gap that we didn't fill very well."
"On top of that we were doing the transition from 50 percent to 60 percent models in the wind tunnel, and there were a lot of other things in the aero group as well. It did have an impact."
Brawn said that the shift to 60 percent models was necessary to increase the amount of technical data it could extract from Pirelli's tires.
"Our conclusion was that we would get a much more representative tire at 60 percent than at 50 percent," he added. "Pirelli has to make 50 percent and 60 percent wind tunnel tires. There are only two teams that are still doing 50 percent. Even with Pirelli's best efforts, they're going to be getting better feedback about 60 percent tires than 50 percent. So we wanted to make the move.
"The other thing that has happened over the years is that you're putting more and more equipment inside the wind tunnel model to measure, monitor and check. We just ran out of space in the 50 percent model.
"There were things that we wanted to do that we couldn't do, and we needed the 60 percent model to accommodate those features. Sixty percent is the legal limit you can go to, there is no further step we can make."