HEY, YA KNOW what would be a fun training camp debate? To ponder where the Eagles could least afford to lose a starter. Who is truly irreplaceable?

Let's run down the list. There's thought interrupted by tap on shoulder; colleague points to safety Malcolm Jenkins limping to the sideline with a hamstring strain, to be replaced by, let's see, looks like it's gonna be Ed Reynolds . . .

OK, I think we're done here.

The Eagles boast what should be one of the league's top safety tandems in Jenkins and Rodney McLeod. But should one of them go down, they have Reynolds, a 2014 fifth-round pick who has been waived and signed back to the practice squad twice; special-teams ace Chris Maragos, who is entering his seventh NFL season, with two career starts under his belt; Jaylen Watkins, drafted in the fourth round two years ago as a corner and cut last year, before returning in late November from Buffalo's practice squad; Nick Perry, formerly of the Ravens' practice squad; and Blake Countess, a sixth-round rookie from Auburn.

Defensive tackle Fletcher Cox might be the most dominant force on coordinator Jim Schwartz's unit, but Jenkins is the defense's emotional leader. He and middle linebacker Jordan Hicks bring order out of chaos.

"We need those guys behind (Jenkins and McLeod) to step up. We need to find out who's going to be our third and fourth (safety), and maybe even a potential fifth, with special teams and stuff like that," Schwartz said Thursday. Jenkins was to get an MRI, as was left tackle Jason Peters, who suffered a quad strain. Both injuries seemed relatively minor, pending the tests.

Observers are used to seeing the o-line have to shuffle to sub for Peters, but Jenkins is a practice-field stalwart, who has started all 32 games since signing with the Birds. Tough to think about playing without him.

"When a guy goes down, it's a great opportunity for those other guys to step up, but the opportunity only exists if you take advantage of it, and those guys need to do a better job of taking advantage of it," Schwartz said.

So, ringing endorsement there, Ed.

"For me, make sure I come in there, communicate as well as (Jenkins) does - which I felt I could have done a better job of today - but in the end, just make sure I go out there and play fast, make the plays that come my way, and try not to do too much," Reynolds said.

"I think it's wide open right now. I think (Schwartz) is really looking for that one guy to take it over."

Reynolds said he wants to show "if my number's called, I can do whatever you need me to do, whether it's cover, whether it's play the deep half, deep middle, know all the calls, know all the adjustments, and be able to communicate it with authority. Go out there and just do what he needs a safety to do in this defense."

What does a safety need to do in this defense? Apparently, one will patrol deep and another will play closer to the line, though Schwartz has indicated both need to be able to cover really well. (The days of the old-fashioned "box safety" are over pretty much everywhere.) With the defensive ends often set in a Wide 9 to rush the passer from the outside, there is significant run-stopping pressure on the safeties and linebackers.

"In the run game, definitely," the safeties have to read more than they did in Bill Davis' defense, Maragos said Thursday. "In the pass game, it's pretty simplified. He likes to just let guys go play."

The previous coaching regime saw Watkins as a sort of emergency safety, after Florida used him that way for part of his senior season. The new regime switched Watkins to full-time safety when spring practice began. He's still learning.

"For the first time in years, even college, it seems like I'm in one spot" instead of moving around, Watkins said. "Safety was always, certain packages, (or) a guy goes down, filling in. This will be my first time actually being at safety, if that (continues to be the case)."

Asked what lesson he took from being cut last year, Watkins said he has learned to not worry about whether he'll be moved tomorrow, or how he figures into the depth chart, that he now takes each day as it comes.

"I was trying to get my head caught up in a lot of different things (in 2015) instead of just going out and playing ball, getting better," he said.

Jenkins, 28, is a 6-foot, 204-pound coach on the field who was drafted 14th overall by the Saints in 2009 as a corner. He led the Eagles with 120 tackles last season, by the team's reckoning, and went to the Pro Bowl as an alternate, though he deserved to get in on the original list.

"Obviously, what Malcolm does is pretty unique," Maragos said.

McLeod, the other starter, signed with the Eagles for five years and $35 million this offseason, from the Rams. Maybe he could more or less be Jenkins, if Jenkins ever went down for a prolonged period, but then somebody would have to step up and be McLeod.

"I've got to develop my game, hopefully get to where Malcolm is," McLeod, 26, said. He said the opportunity to learn from Jenkins was a factor in his signing here.

McLeod has been the ballhawk of training camp so far. If there's an interception in practice, chances are, No. 23 got it.

"Right now, I guess I've just got the hot hand," he said.

"Those guys are good players for a reason," Schwartz said of his starting safeties. "They come to work every day. they're a great example to the rest of the secondary on how to be a pro. How to be in the right spots.

"When I said we haven't been consistent as a defense, I'm exempting those two guys. Because they've played very, very consistently. They're great communicators. We need more guys following that suit."