Does it work for anyone? There was an update and the BG didn't change at all, no Open Captain Selection..
Description from patch notes
Open Captain Selection To improve team balance and give players more control over team composition, Captain Selection is now available in Battleground.
How It Works When all matched players are Legend rank or above, there is a chance to trigger a Legendary Duel.
In this phase, the two highest-rated players become captains.
Captains take turns selecting their teammates in a draft format.
Draft Rules Each captain selects 3 teammates. The draft follows a structured pick order. Each selection has a 15-second time limit. If a captain does not make a selection in time, the system will assign a player automatically. The remaining players will be assigned by the system. Additional Notes During Legendary Duel, player stats are not compressed, and all players gain additional damage reduction.
Players who leave during the selection phase will be treated as refusing the match and may receive penalties.
This feature is available in Battleground Classic mode (Assault).