His top competition for the second safety spot is 2013 fifth-round pick Earl Wolff, who started six games last season.
"Nate's the first guy up, and Earl is in running with the second group right now," coach Chip Kelly said. "Both have done a great job in the offseason program. We're excited to see those guys play it out."
The Eagles also have Chris Maragos, who excelled on special teams with the Seattle Seahawks; fifth-round pick Ed Reynolds; second-year safety Keelan Johnson; and undrafted rookie Daytawion Lowe.
When Allen signed, he had no assurances that he would start. The free agent spoke to other teams, but all the offers were for one year. With the Eagles offering the same, Allen decided to stay in the system he knows.
He opened his career with Sean McDermott as his defensive coordinator, then played for Juan Castillo and Todd Bowles before the current coaching staff was hired last season. That resulted in the best season of his career, and there is optimism in the NovaCare Complex that Allen could be blooming late.
"Still always learning, but not scrambling," Allen said of his second year under Bill Davis. "If you make mistakes, you can correct them, just building off what you already know."
General manager Howie Roseman alluded to the enticing physical characteristics that made the Eagles target Allen in 2010 - at 6-foot-1 and 210 pounds, Allen remains the Eagles' biggest safety - and said the changes in defensive systems could have stunted Allen's growth.
"He's finally in the same system for the second year, and you've got to be able to play fast," Roseman said. "It's very hard on a safety going through all those system changes."
Allen's role has not changed from last year, even with the addition of Jenkins. The Eagles do not use a free safety and strong safety. Instead they use their safeties interchangeably. They want them to be able to play deep and in the box. Jenkins will handle the defensive calls in the secondary, and an upgrade at that spot can help Allen. The Eagles have started eight other safeties during Allen's four seasons in Philadelphia. Other than Quintin Mikell, it's been a mostly undistinguished cast.
One of those players was Wolff. The Eagles hope that Wolff improves the way many players do in their second season. Much of that development occurs during the first full offseason, and Roseman said Wolff's work ethic is "off the charts." Wolff has latched on to Jenkins to soak up knowledge from the Eagles' new safety.
"I already know what the call's going to be," Wolff said about the difference in his second season. "I see things faster, I read things faster, I really can't wait to see what kind of jump I'm going to have from Year 1 to Year 2."
Neither Allen nor Wolff will remind Eagles fans of Seattle's Earl Thomas. They were both part of the NFL's worst pass defense last season. If the Eagles had selected Ha Ha Clinton-Dix or another safety in the first round, then the conversation could be different. But the way it stands now, Allen is on pace to open his fifth season with the Eagles as the starter.
"I didn't know what was going to happen," Allen said. "I was just coming in . . . and let everything fall into place."
Eagles beat writers Jeff McLane (@Jeff_McLane) and Zach Berman (@zberm) look at each position on The Inquirer's Eagles blog, "Birds' Eye View," through June 12 at inquirer.com/bev