because #5 corners get few reps at corner, other than as a dime back
We have no idea where Logan Ryan will end up in the CB race. He could in theory, play well in camp and jump ahead of either Arrington or Dennard. Belichick could move either one of those players just as well, as he prefers to test different players in different spots in the secondary for depth and emergency purposes (he pretty much stated as much in his comments).
There's also the fact that we have injuries every single year, so not only are you assuming the fact that he cannot beat out any of the other 2 players in front of him (Arrington, Dennard), you are also assuming full health at the position of CB. That seems short-sighted
in my opinion. You could be right, of course.
The reason Belichick is moving Ryan to safety is because he wants him to get more reps.
This is pure speculation, and while you could be right, so could anyone else who believes otherwise. So, in your opinion:
1. There will be no injuries or games missed from CBs this year
2. L.Ryan is not talented enough, nor does he have the potential to jump in front of Arrington or Dennard at any point during the year
3. Camp battles have already been won, therefore making L.Ryan a CB5 for the rest of the season
4. Belichick is giving him reps at safety not due to the fact that he prefers to have versatility and depth, but that he is specifically looking to get one player on the team (Ryan) more looks