Cyrus Jones was NOT a bad player. Reports are he's a likely starter for the Ravens. There are a LOT of situations that can cause a player to get let go. Wilson was stuck in the S glut that was McCourty, Chung, Harmon, but he's been a productive starter for the Lions for 3 years now. Dawson was the 7th man in a 6 man depth chart, but the guys he was behind make up the best and deepest secondary in the league. He probably was good enough to make 90% of the rest of the league's rosters
Of that group, only Richards was an out and out failure. The others were proven to be good football players who for some reason or another just didn't fit in this system. Either there was a glut of other good player at their positions or injuries and how they affected their development.
BTW- It just occurred to me that every one of the players you listed were DB's, a position of strength of the Pats for many years. Curious, don't you think? You know what I think it indicates? Bill shows that is one step ahead of the game when he realized the only way to compete with today's rules and passing attacks is to be great in the secondary. And that is why we see him year after year loading up on DB's
As much as I love tall CB's, I was irate with the Williams pick, just because we looked so strong at CB to begin with....and I was wrong again. Bill understood that you can never be too good in the secondary and Williams was a unique talent that you couldn't pass up, even in a crowded CB room. And after a slow start, he has shown why this pick will end up in the Gronk, Volmer category in the end. He will be an amazing match up asset this year.