I don't think lag was too much of a factor, though. Maybe for a few of the waves, but BD would've lagged for 5 seconds, yet still have 4 hits same second, which isn't reasonable to me.
It happens. I've had perfect 4+1 waves (I launch 5 waves if I have the catas)...... taking 10 seconds to be sent. Can't say if that was the case here of course, but it happens.