Maybe this was covered in another thread...if so, sorry for the repeat.
4/10 @ B-40. QB A1 is sacked at the 50. After the play, B99 celebrates/taunts the QB. My question is does the auto-first down occur before we have a new series for B? If we had a DB PF, we would still be giving the ball to B, backed up 15 yards from the SS. DB UNSs still work the same way they always have?