$10 for a bar tab on league night per player is probably way to low and you could probably double that to $20 per person depending on location.
I play on two leagues. Was on 3 until I dropped the APA. Here is what I see.
Most of the very best players don't drink anything except water, juice or coffee. They usually play and run. Unless it is the BCA where they can't because of the round robin.
The majority will buy one drink and then have the free team drink.
Only the ball bangers will drink like fish because they are just out for a good time and don't really take the game too serious.
I don't really see that a bar benefits from a league unless their home team is a bunch of ball bangers.
Our APA team had the most drinkers.
If a player has 4 beers it only amounts to $10 and most times the leagues are played when there are daily specials or promos such as Monday Night Football or game day where beers are $1. Or Tues night when Corona is $2, or pitcher specials for $4 when any home professional team is on TV.
One bar gave free drinks when the Red Wings scored or the TIgers hit a home run (Detroit Area), but you had to call out to the bartender. It wasn't automatic.
Granted it still fills the bars when they would otherwise be empty.