I think you missed the qualifier "At least in OTL" here somewhere. Because of the changing situation from early '15 on using OTL late '16 and on presents the problem of how relevant it would be here.Late 1916 and Early 1917 looked very good for the Entente. The Somme and Verdun had been hard fought but were seen (to some degree correctly) as victories that had dealt severe body blows to the German Army. American entry into the war in early 1917 assured the Entente was the better resourced of the two alliances and that large reinforcements were possible (becoming more assured as the year went on).
That is not to say that general trends are worthless, such as trade patterns and longterm industrial production, but baseing military actions from OTL here could be very missleading. That is one point as to why I am leary of the Brusilow Offensive here. Without the Italian Adventure of the Austrians, the results could very well be massively different. And that could have further waves for the Germans that do not need as much force to hold it. Maybe add those to the Somme and the balance may shift.
Again, that would be something only the writer could clear up.
TLR using OTL circumstances after more then a year of changes is suspect in my opinion.