1.) The Dolphins have a lot of talented WRs to evaluate. That is hard in a preseason game when your 2nd and 3rd QB are not playing and you have to play a guy that has been on the team for less than a couple weeks. Bottom line Miami had to get someone in that can allow them to evaluate the other players they need to make a decision on.
2.) Matt Moore has a shoulder problem. There has to be something to this. Is he one hard tackle away from being down for the year? Maybe he is even considering surgery now. I have to think Joe Philbin has been waking up in a cold sweat at night thinking of Tannehill getting hurt for the year in game one and his QB for the year is Pat Devlin. He may as well kiss his job good bye in that case.
3.) Miami has more depth than they have in many seasons at key positions like WR and Dline. I think they are already planning to keep only 2 QBs. I think they will take a hard look at getting a practice squad QB. Seth Lobato has the inside track on making the practice squad which is why he is still on the team and Devlin is gone.
4.) Matt Moore is paid a lot of money for a back-up QB. The reason is he is one of the best back-ups in the league. If he has a chronic issue with his shoulder that may require surgery. The Dolphins may not want to pay him a premium salary in order to help them save money on the cap for next years free agents.
So to summarize it up, I think at this time the Dolphins are planning to only keep 2 quarterbacks and Matt Moore has some shoulder problems. Pat Devlin has not been healthy either so it makes sense to let him go now. I personally don’t think that Matt Moore’s job is in jeopardy. However, the Dolphins are being safe and bringing in a veteran in case he is not ready to go. I find it hard to believe that the Dolphins would seriously consider cutting Moore for Quinn for a salary cap move only. It would have to be because he has a health issue. It will be interesting to see if Moore plays in the next preseason game and how his throws look if he does.