Ross Brawn made a comment before Australia which stood out. He stated that the other teams still blowing exhaust gases to the lower rear of their car externally would suffer higher tyre degradation due to the extra heat.
"Some teams have gone for a design that is clearly still blowing the exhaust in the area of the rear tyre – that may have an effect when rear tyre degradation is critical because it is much more difficult to manage where the exhaust flow goes this year than it was last year. Last year it was quite precise, this year it is more general because you cannot have the exhaust pipes to blow through the diffuser.
"There will be some interestings twists and turns over the first few races."
The fact that Merc didnt have a similar exhaust system in place yet still suffered bad tyre degradation has me slightly concerned. It does make you wonder if they will be able to revise and apply their exhaust system similar to Mclaren/Red Bull/Sauber at all at the risk of even higher degradation.