Brawn GP was the legacy of a hugely expensive project formerly owned by Honda who had also elected to buy the team from the well established BAR who in 1999 had bought the team from Ken Tyrell. This year (2012) is the third iteration under the Mercedes marque which as a project was supposed to bear fruit as a manufacturer in its own right rather than just be an engine manufacturer. (Just as its previous owners Honda were looking to do) The trouble is always one of transition, time and of course money. Lets look a further back down the line to see how Mercedes current struggles can also be attributed to the past and where they are going to go from here.
The KERS technology was not passed onto the Brawn outfit and/or would have been difficult to implement with the Mercedes engine due to the crank position, cost and purely timing, KERS wasn't possible for the team to introduce in 09. As other teams struggled to utilize their own KERS systems Brawn were able to move ballast around their car but mainly loaded their bib/tea tray area with ballast echoing the weight distribution ethos that the RA109 equipped with KERS may have had. KERS packages in 09 weighed around 30KG's which is a substantial amount of weight when you consider being able to put this wherever you like in the car. The likes of McLaren & Ferrari had to place their heavy systems in certain places to utilize cooling and weight distribution.
The WO1, Mercedes first car in F1 since the 50's was flawed for many reasons although the Brawn GP team had been world champions in 09 they neither had the resources or money to contest the battle for 09 and produce another championship winning car for 2010. When design focus was needed to be placed on the 2010 car during the 09 season both Jenson Button and Rubens Barrichello were at the helm of the BGP001 neither of which drove in Mercedes first season compromising the W01 with traits that perhaps their new driver line up of Michael Schumacher and Nico Rosberg wouldn't like. Michael returned to the sport in 2010 after a 3 year absence in which time he spent the first year as an advisor to Ferrari and continued his motorsport journey on two wheels until at which point he had an accident and injured his shoulder. It was afterall this injury that had stopped his return for Ferrari in 09 for the injured Massa at Ferrari and reignited Michaels passion to be in F1.
The largest changes from the BGP001 to the WO1 came in the form of the higher ridged nose/bulkhead as I alluded to earlier that the team had taken a cue from Red Bull and in a latter upgrade a blade style roll over hoop with twin airbox entries either side.
Above: The original Mercedes WO2 Exhaust design
It took Mercedes until Valencia to converge on the Red Bull solution who had their exhausts exiting much more rearward and enclosed in a tunnel above the floor to the outside edge of the floor sealing the diffuser much further back and eliminating the effects of tyre squirt (see my tyre squirt article). Even with the FIA curtailing the off throttle effect this remained the most effective way of getting a diffuser sealing effect.
My theory is based on the slots under the front wing making the wing work when blown. This is based on the assumption that when Mercedes originally tested the 'W' duct it was in order to create additional downforce aswell as reducing drag. Wings can only create so much downforce, this can either be done by dimensionally adding more wing or by increasing the angle of attack. The size of the flaps available to F1 designers is heavily restricted in order to limit the downforce available, they can add gurney flaps but these will add drag and so on the front wing are usually limited in size. Wing angle of attack (AoA) can effect how much downforce is generated but once again at the compromise of drag. I'd guess 15 degrees is about the stalling level of a wing (ie the point at which it won't create additional downforce and stalls) if you were to blow the rear face of the wing you can elevate the wing angle by perhaps another 5 degrees before it stalls. This gives you the advantage of being able to run a higher AoA than if you didn't blow it, resulting in a net increase in downforce.
Above: Cascadeless Front Wing adopted from Montreal onwards
Since Montreal, Mercedes have run their front wing without the cascades which again highlights that they may have been creating too much front end downforce and the cascades creating drag as a net result. (They also changed their wing pylon design to a very McLaren-esque design) I believe the wing from the WO2 with the hole in front of the wing planes paved the way for this, with the designers wanting the air to be forced in behind the main planes to allow a higher AoA. Being able to do this without the need for the through hole would be more efficient.
Some of Nico's quickest lap times at the start of the season saw him deactivating DRS prior to the braking phase which if my theory is correct would see the front wing becoming blown restoring front end downforce and balance for cornering/braking.
Mercedes DDRS is really a qualifying enhancement and if my theory serves correct becomes more of a hamper as the race goes on. This is due to pitch angle, as the fuel burns off during a race the AoA on wings alter ever so slightly which puts the car through an evolution process. This could be part of the reason for Mercedes tyre struggles (again speculation).
Although initially the Lotus system was hailed a DDRS it would now appear it is very much a passive F duct system much like the one that Mercedes ran on the WO2 so if Mercedes are prepared to take their closest championship rivals on there is no reason why they couldn't employ a similar system to reduce drag on the lower plane like Lotus: http://somersf1.blogspot.co.uk/2012/08/lotus-e20-passive-f-duct-system.html (TDRS anyone?)