I think Emery has got it right as Auba is kept, relatively, fresh with Laca dealing with the pummelling premiership strikers have to endure.
My oft-repeated criticism has been with the players as i think they should be developing an understanding that gives them an edge over set defences. I don't even think one of them has to sacrifice themselves to play a 9.5 like Firminho/Benzema but maybe i'm biased by referencing the outdated nineties football of Signori/Casiraghi, Asprilla/Zola, Bebeto/Romario, Romario/Ronaldo and Cole/Yorke?
It's not a major issue as 35 goals between them is pretty good and it should be noted that there are other top strikers (Jesus/Aguero, Kane/Son and CRonaldo/Dybala) who suffer a similar problem.