I've had some HSB in my ponds to maybe 5-7 lbs. I've always felt their mouths are not that big, but I was thinking about them eating 4" plus BCP.
I've seen them clean up on schooling fish so I see your point about them getting the YOY BCP.
Excerpt from Robert Crais' "The Monkey's Raincoat:" "She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."