Well if we are talking this years LB vs last years LB then I'd have to agree that mills is better. I like mills, if he was our player I'd pick him over grounds. since he isn't out player and now we have a CB I'd move grounds into LB cos we know he can do a job there, and do it well.
Mills is here for such a short time, seems daft to have him first choice over a player we all know can improve.