I have to respectfully disagree with that. A number 1 and a number 2 driver in the top teams has been the normal situation in F1 as long as there has been racing for the exact reason of the constructors championship. The team do not want their own drivers risking fighting each other. The only times I can think of whilst I've been watching F1 where team mates have been truly allowed to fight for the title was Hamilton/Rosberg in 14, 15 16, Senna/Prost in 88 89, and Prost/Lauda in 84/85. In all these situations the teams had such superiority over the rest of the field that it's not mattered if they squabble. All those situations eventually ended in tears. Other examples I can think of were Mansell/Piquet in 86 where their squabbling cost them the title and Vettel/Webber in 2010 which nearly cost then the title. I think when Merc realised Ferrari could beat them this year they switch tactics. Which happens to be at the exact same time as Bottas 'form drop'. Form that suddenly picked up by the way as soon as Lewis was champion.