I have a bad news for you, Chicken Claw.
Our capture-the-leader-first theory didn't seem to work on theses Night Pirates. We thought it should have create a disturbance among them once their boss had been taken out.
But these heartless punks produced another captain unexpectedly soon. They seem to be already very comfortable with boss being changed, possibly due to the constant mutiny among them.
I guess it might work a little bit well to knock down those minions if we want to weaken the strength of these pirates. Kill as many as you can!