During season 21, it was a hero pool. It was very much decided by blizzard. I don’t have the fainted idea when OWL had player chosen hero bans but it. was. pools.
This isn’t what a hero ban is when as it is understood by the larger competitive esports scene. Hero bans are done right before a match and they’re for that match alone.
You’ll have to dig up what games you’re talking about where an OWL team was picking the bans before the game on stage, because I can’t find who played such a game, and what was banned.