In the dragon ball super manga it was shown that Trunks was almost as strong as ssj3 Goku.
Trunks wasn't even able to beat base Black Goku, but he did confirm he fought ssj Black before.
When Vegeta goes ssj 2 Black holds his own but is losing. This part is fine because I can live with ssj2 Trunks<base Black<ssj2 Vegeta, though even that doesn't make much sense because ssj2 Vegeta should be on par with ssj2 Goku who is weaker than ssj2 Trunks.
However then Black either goes ssj or ssj2 and he is still losing to ssj2 Vegeta. This pretty much means Black didn't even get 2x stronger. If he did get 50x or 100x stronger then that would mean ssj2 Vegeta is also 50 or 100x stronger than ssj3 Goku...
So basically the manga is telling me.
full powered ssj2 Trunks<ssj3 Goku=<base Black<ssj Black<ssj2 Vegeta
Which really doesn't make any sense.
Either that or Goku was severely suppressing his ssj3 power, but then why would he use his SSG form to oneshot Trunks? And even if he was that wouldn't fix how ssj only made Black like 50% stronger. It didn't even seem like a 2x boost.
Though props to the manga for actually making the character look strong when they are fighting and not having building level final flashes and still somehow having better power scaling than the anime.