Post Player

[guille]

Here is another situation (NCCA rules):

A1 is a post player and has the ball backing up on B1 aggressively. B1 has his forearm across A1's back trying to stop his progress to the basket. When the pushing by A1 becomes a foul and when the pushing by B1 becomes a foul?

Also could you mention the rule number as well?

Thanks!