The second-year safety's struggles didn't just pop up on Thursday night out of thin air. It's been an ongoing problem since the Eagles selected the Temple product two to three rounds before most - if not all - draft analysts had projected him to be taken.
Last year's issues were attributed mostly to the lockout. To use last year's work stoppage as an excuse for Jarrett's slow development was fair. While some rookies had no problem making the adjustment, Jarrett was playing a cerebral position that had responsibilities unlike those he had on North Broad Street.
Jarrett was, in essence, a fourth linebacker at Temple, a smash-mouth tackler who helped shut down the running game. His cover skills were suspect, however. When he ran the 40-yard dash in 4.62 seconds at the combine, it did little to ease concerns about how he would transition into the pass-heavy NFL.
The Eagles thought Jarrett someday would complement Allen, who had been selected in the second round a year earlier. But the team altered the responsibilities of its safeties last year when it brought defensive-line coach Jim Washburn on board.
Because the front four would have less to do with playing the run, the safeties would have outside gap assignments. So the safeties, more than ever, would have to be interchangeable and play both the run and pass, ideally at the same level.
Jarrett wasn't alone in struggling to learn the system. But there were other signs that he just might not be able to compete. In the 12 games in which he was active, Jarrett made only two tackles on special teams.
His biggest issue was and continues to be footwork, in both his backpedal and when he breaks to either cover a receiver or come up to tackle a ballcarrier. And because he doesn't have elite-level speed, Jarrett has to be precise in his footwork.
"Working on your footwork is repetitive," Jarrett said.
Allen said that it's an area in which defensive backs always can improve, but that "every [defensive back] has to have some amount of footwork - naturally."
In Thursday's game, Jarrett wildly missed on two tackle attempts when he took bad angles. Of greater concern may have been the 2-yard touchdown pass that Steelers receiver Emmanuel Sanders caught right in front of the slow-reacting safety.
"We all saw it," coach Andy Reid said Saturday. "He can work on his angles and he can work on his tackling. Those are things that he did very well in college."
But this isn't college. It was a reach the Eagles, desperate for a hard-hitting safety, so clearly made. Leading up to this year's draft, general manager Howie Roseman said a number of times that the Eagles would not stray from their board just to fill a position of need. He never mentioned Jarrett, but it was understood which past mistakes he meant.
Jarrett, by all accounts, is a hard worker and a stand-up guy. He did not shirk responsibility for his poor play Thursday. But the question has to be asked: Will he be able to grasp the concepts quickly enough to make up for what he lacks in athleticism?
"It's always frustrating to not play well," Jarrett said. "But I'm going to bounce back [by] looking at the game film and correcting my mistakes and not letting it happen again."
Reid has cut early ties with one of his second-round picks before. Quinton Caver, taken 55th overall in the 2001 draft, lasted six games into his second season. But the linebacker couldn't even contribute on special teams, and when the Eagles had the opportunity to pick up Keith Adams, they released Caver.
The Eagles' safety situation is anything but settled. Allen and Kurt Coleman are the starters. Both were benched at some point last season. Allen appears to be over his knee injury. Coleman has looked sharp in camp.
But if either gets hurt, the Eagles' next option at this point would be veteran O.J. Atogwe. He isn't a bad substitute, but he's still learning the system. Tom Nelson split reps with Jarrett on Sunday and had more second-team snaps by Monday.
The last safety spot could come down to Nelson or Jarrett if Colt Anderson, who is recovering from a torn anterior cruciate ligament, starts the season on the physically unable to perform list.
Or they could comb the waiver wire - where Jarrett could find himself in three weeks, if he doesn't show signs of improving.
Contact Jeff McLane at 215-854-4745 or firstname.lastname@example.org. Follow on Twitter @Jeff_McLane.