Some of it is a mindset. Some of it is superior conditioning, even at this point in the year. And as we all wonder about what the second year under Chip Kelly will look like, some of that will be about the second year of the whole "sports science" business. It seems to be a significant part of the evolution.
"The guys who have been here have gotten used to what the pace is, what to expect," safety Nate Allen was saying the other day. "That's normal for us. Playing fast is a normal pace for us. The rookies, it took a little while to get used to it. But now everybody's coming along . . .
"I feel healthy [in Year 2]. I feel not as worn out sometimes. When you get into this OTA regimen - we just feel fresh every day and not as run down. We get the right rest and nutrition, and that all plays a big part in it."
When people talk about how the second season will be tougher in some ways for the Eagles, they talk mostly about how the schedule appears to be harder and how everyone around the league has had an offseason to study exactly what hath Chip wrought. But another obstacle is health - because the Eagles were almost freakishly healthy last season, and everyone is having a hard time figuring out how much of that was the Eagles' approach to conditioning and how much of it was just luck.
The numbers were compiled at the end of last season by the Dallas Morning News. Eagles players projected as starters missed only 29 games last season, 16 by wide receiver Jeremy Maclin. That was the fourth-lowest total in the NFL in 2013. Only the Jets (20), Chiefs (22) and Redskins (22) had fewer injuries.
During the season, the Eagles had 14 players who started every regular-season game. No team had as many.
"We put a huge emphasis with the Eagles on recovery," center Jason Kelce said. "I think that's one of the things that helped us stay injury-free last year, for the most part. A lot of that came down to luck, too - it's just kind of the way it goes. But the organization and the strength and conditioning department puts a huge emphasis on rest. A lot of the things that bigger guys have problems with is sleeping right . . .
"They're big on making sure you're getting the right amount of sleep, eating right, hydration, al that stuff."
One of the ongoing conversations, Kelce said, involves sleep apnea, which can be an issue for bigger people. If there is a sense that it might be an issue for a player, Kelce said, the club encourages medical consultations.
"I've been kind of on the fence," Kelce said. "I've been sleeping good right now but sometimes when I put my weight up, which I have been doing [for the season], I start developing what I think is called weight-induced sleep apnea, where your neck is too big. I might get tested later on down the line, toward the season. Right now, I'm not having a problem."
That is just one small example of the kind of detail involved in Kelly's program. Sleep apnea is certainly not an unknown condition in NFL locker rooms, and there has been discussion about it, at least on some level, for years. But discussion and action are different things.
So you just add it to the list: diet, cardio, strength, recovery, sleep. Last year, for some players, must have seemed like a revolution.
"It's been easier to adapt to those changes because you're only adapting to two or three different new things, whereas last year, it was just a complete wholesale new deal," Kelce said. "This year, we know what to expect. We know what's going on . . .
"More guys are utilizing [the program] this year, especially at this point. I think by the end of last season, pretty much the entire team was utilizing it pretty well. But now, a lot of guys are utilizing it just for maintenance throughout OTAs and just the offseason in general."
As it turned out, the results were the program's biggest selling point. It isn't as if a rookie like safety Earl Wolff was a skeptic last season, but it was all new to him. He undoubtedly arrived with a bit of the rookie's bulletproof sensibilities, but he found out what the NFL can be like soon enough, struggling with a knee injury down the stretch of the season.
Now, he says, "I'm feeling great, man," Wolff said. And this is what he said he learned:
"Honestly, last year I would do a little bit of extra work - but not as much as I'm doing now," Wolff said. "When I say 'extra,' I mean staying after, getting a hot tub, getting a cold tub, stretching after every practice, doing core work after every practice. It's those things - and, honestly, I learned that from the veterans. I watched them last year and I saw how their bodies were holding up, and I want my body to be the same way when it gets to that time."
Theory, practice, results - and now we get to see if those results can mitigate the law of averages.
On Twitter: @theidlerich