Matt Moore has played well and out played the starter almost every time he has been given a shot. His QBR was 3rd in the league last year in the games he played. If you look at the dolphins offensives performance in seasons where Moore played, they look much closer to a top half team. That's not always the case with them.
I am not in the practices to tell you why he has never gotten a look as a starter. I can only tell you what I can assume. The last few times when Moore's contract ran out, he chose to resign in Miami and stay a backup (Rather then go out and compete for a job with some other team)I'm not sure if that helps my case. Perhaps he is content with living in south beach, taking less hits, having less pressure and still getting paid. I can't give you an answer for why he has stayed a backup but it's not as if every coach in the league, always plays the best guy. We have seen players shine when given the chance in every sport. We have seen the Bills start QBs because of draft status and not ability, more then once. The best QB on a roster is not always the starter.
Maybe the fact that he has stayed a backup is more about bad coaching and not about his play. All I know is that when we have played Miami in the past few years, I would much rather see Tannehill then Moore. Hopefully I am in the minority here, because all I want from the dolphins are losing efforts.