BM's dps is absolutely fine. I top the majority of our fights in heroic and mythic, the only thing that I'm waiting to see is how it transitions in the next tier with scaling.
I didn't play BM in Legion but from what I saw, BM's scaling was pretty atrocious as the expansion progressed through later content patches and higher tiers.
So we'll see, but honestly I wouldn't go off those logs. If you're performing well then those logs don't matter.