Regarding Byrd - From a CNNSI Article http://nfl.si.com/2013/08/06/all-underrated-team-defense-jabaal-sheard/?sct=nfl_t1t_a1
Byrd frequently gets bashed by people looking at stats without understanding their schematic context — yes, he is usually among the league leaders in yards per pass allowed (14.3 in 2012), but that’s because he’s playing center field so often, and he’s usually (and literally) Buffalo’s last line of defense. In 2012, he allowed just 16 receptions as the primary target on 561 coverage snaps, picked off five passes and allowed no touchdowns. That last stat is especially impressive for a deep safety. Oh, yeah — he was one of PFF’s highest-rated safeties as a run defender. Byrd is now a great all-around player and should be recognized as such.
It is not about the injury this year. It is more about injuring before the season starts. If he is injured in training camp, the 1-year salary is not guaranteed (Only if you are on the day 1 roster).