According to Bleeding Green Nation, the Eagles came to the decision at least partially because of the injury that starting wideout Jeremy Maclin suffered in the team's season-opening 17-16 win over the Cleveland Browns on Sunday. It's certainly possible Maclin will be ready for Philadelphia's Week 2 matchup with the Baltimore Ravens, but it's not a chance the team wants to take.
As for Jarrett, he just didn't do enough to warrant more time in Philadelphia. The once-promising prospect never showed much, during which he was active for 12 games and made 22 total tackles, by the team's count.
The Eagles are still stocked at safety with four on the active roster. Of course Kurt Coleman and Nate Allen are the starters, with David Sims as the primary backup should either get hurt. Colt Anderson, primarily a special teamer, is on the team's 53-man roster, but has been rehabbing a knee injury.