What they cannot know, of course, is how well they have replaced the talent and leadership they lost in Michael Vick, Jason Avant and, of course, lightning rod receiver DeSean Jackson.
Perhaps the Eagles will be able to gauge that better in a month at training camp, when the heat and the hitting begins.
Perhaps they won't know until after preseason games; or, more likely, until after the season's first month.
Despite all the recent sideline analysis - estimating whether Nick Foles' arm strength improved, whether Jeremy Maclin's knee is sound, whether first-round linebacker Marcus Smith is good enough to do more than block for the kick-return unit - despite all of the non-contact hubbub, there is no definitive way to determine if the team got better.
"You can even tell right here," said center Jason Kelce. "I'm more comfortable making calls, identifying the corrections of certain plays, and making the right calls, and everything else. All of that is inserted into my brain.
"I can get the calls out quicker, so the quicker I get the calls out the quicker the guys around me process why I'm making those calls, and make the corrections. For me, that's the biggest correction."
Certainly, the offensive line should be appreciably improved. It wasn't until June of last year that Kelce returned from his knee injury. Todd Herremans was coming off an injury, too, and was converting to right guard after stints at left guard and right tackle. Left tackle Jason Peters had missed 2012 with Achilles' tendon injuries, right tackle Lane Johnson was a rookie running with the second team.
The line returns intact. Johnson is leaner and, of course, more experienced. Herremans' issues both with lingering injury troubles and with learning a new position are past. Peters resolved his injury problems and his adjustments to the new coaching style by midseason of last year.
Only the offensive and defensive lines remain unchanged.
The most gaping hole, of course, was left when the team cut Jackson in March, then left him to deal with reports that his association with gangs and his unprofessional conduct with Kelly and his staff led to his dismissal. The team eventually denied those issues led to Jackson's release, but the message was sent: No degree of talent ensures a spot on the roster.
Jackson, only 27, caught 82 passes for 1,332 yards and nine touchdowns. No Eagles receiver on the roster has ever approached those comprehensive numbers, and only Maclin is in the ballpark. Maclin missed 2013 with his second knee reconstruction in 7 years, and he allows that, in these camps, he has not regained full confidence in the joint.
Things might be less unsettled among the receivers if the team had retained slot receiver Jason Avant. The toughest player on the team, Avant also served as a mentor for every troubled Eagle for the past 5 years, from Vick to Jackson to Riley Cooper.
Avant appeared to have lost a step last season, and has been replaced with 6-3 second-rounder Jordan Matthews - similarly driven, if unproven. Will he make the tough catches in traffic, absorb the beatings Avant endured and contribute on special teams?
The Eagles might not know for months; maybe years.
What they do know is that, while Matthews runs fast once he gets going, it takes a few steps for him to reach cruising speed . . . as long as he's going in a straight line.
Running back Darren Sproles and safety Malcolm Jenkins are two undeniable upgrades; but then, hiring a veteran sparkplug to back up the league's best running back, LeSean McCoy, seems a bit of a luxury. And, while Jenkins has a good reputation as a conservative tackler, he isn't expected to make a bunch of big plays.
Still, as long as Jenkins learns quickly, the defense - unchanged except for him - largely should be a known, dependable entity. This was mostly about learning, anyway.
"You can figure out who can mentally handle what we're doing," said linebacker Connor Barwin, who is going through his sixth spring of OTAs and minicamps. "You can see what kind of group you've got. Nobody in this group complained the whole 10 weeks. We advanced ourselves mentally."
Ideally, that means the defense should react better than it did against the Saints.
"Guys are more instinctive. And some guys just look better than they did last year. The package is just so much farther along," Barwin said. "Where we're going to go into training camp is so much farther than where we were. Instead of teaching guys all through training camp last year just where to be, this year we'll go to camp teaching guys how to do it."
Even training camp cannot entirely project the team's soundness, especially at the most important spot: quarterback.
Don't forget: Nick Foles last season stole the job from Vick after Vick badly injured his hamstring, and Foles missed a start with a concussion.
Vick graciously occupied the backup role last season and, in the locker room, helped quell the unrest that followed the news of Cooper spewing a racial epithet. Vick's rocket arm and athleticism and his moderate success in Kelly's system in August and September made him a spectacular backup, but the Eagles did not re-sign him.
So, at some point this season, Mark Sanchez or Matt Barkley or G.J. Kinne will have to throw a pass in a game. None seems ready today. There is no certainty that any will be any more ready when Jacksonville visits Sept. 7.
"Until you get them in games, because they're not getting hit," you can't tell, Kelly said. "You get a feel for what they're like when they get a chance to perform in those preseason games. I've seen improvement from them in these drills, but you're not going to find out until you put them in a game."
They're not the only ones.
On Twitter: @inkstainedretch