On BF1 you can use certain tweaks. One of wich is the configuration of the amount of threads the game can use. You can add the commands listed below in a User.cfg file in the main BF1 folder. The engine does have certain limits. The game wont run if you're using less then 3 threads and it will also crash when you try to run it with more then 11 threads.
By default, the game is configured so that it uses 4 threads.
I've run this test on only one resolution. That is 1080P, Ultra settings with 130% resolution scale.
I noticed that with the maximum of 3 threads, my CPU boost went up to 4225Mhz on the active cores but while running 11 threads, the CPU boost went no higher then 3950Mhz.
As you can see, the minimum framerate stayed the same, but the avarage and maximum FPS did increase, providing smoother gameplay. Not only that, power usage was lower and the CPU and case temperature was lower.
My conclusion: Battlefield can use up to 11 threads, but becides increasing CPU usage, they don't benifit the gaming experience at all. That's probably the reason why the game is configured to use 4 threads max by default. 3 threads @ 4.225Mhz provide higher framerates then 11 threads at 3950Mhz. Probably the same reason why Intel is confident about the 9700K, wich has less threads, but higher clockspeeds then the 8700K.
It would be great if other Ryzen 2x users did the same test and share their results.