Both engine and chassis were supreme, hence the advantage of Mercedes.
I still believe the merc chassis beats the RBR's, sometimes slightly, sometimes with a huge advantage (depending on which track).
The engine of course plays it's part too but I'm sick of all the mentioning: it was all the engine of merc that gave them this advantage. Those people clearly don't have a clue. Renault made massive strides and all this Horner blabla (we're 50hp down, )is all crap!
It's the total package that counts. That's why rbr leapfrogged Ferrari after their engine upgrade.
Mercedes AMG + Hamilton => dreamteam!