I’d assume they have to know by reading these forums. Plus, I’m sure they’re very familiar with Anchor’s grading system too. So far, they’ve released extremely popular heroes in all rounds. Hel was probably first because she’s one of the most favored (and she was the first HOTM), Alby & Ares together was crazy (but right after Pirates which is the worst event for $$ coming in), then Athena.
I wanna say they know which heroes are more desired than others, especially if they plan to remarket them all. Then, they should know in order to make the most out of their sales and plan accordingly. Of course I don’t know that for certain, but from a business perspective, that would be the smartest move.