It encapsulates, simply, his endless drive to apply logic to every detail of his work and his need to understand every element that's being put in place around him.
So after three days of joint practices with the New England Patriots here on the south side of town -- some 3,000 miles away from the Pacific Northwest -- and after Tom Brady spent the better part of Tuesday and Wednesday treating Philadelphia Eagles defensive backs like Kelly's Oregon teams used to treat Washington State, the time seemed right to turn the tables on the heralded NFL newcomer.
"The challenge of it," he responded, leaning against the side of a wall outside the NovaCare Complex, a state-of-the-art NFL facility that still falls short of the gleaming "Football Performance Center" that his old employer just built. "The chance to compete against the best coaches out there, the best players out there, in what I think is the best league in the world; it was the challenge part of it."
On Friday night, the public will get its first glimpse of what those on the outside view as the Eagles' grand experiment -- and what Kelly sees as his greatest challenge.
Through organized team activities, minicamps and now training camps around the league, two questions have invariably come up in my conversations with coaches, scouts and execs: "Have you been to Philly?" and "What are the Eagles gonna look like?"
All indications are that, when the Eagles and Patriots kick off their preseason matchup at 7:30 p.m. ET on Friday, we won't get much of an answer to that second question. Nor will we get an answer next week ... or the week after that ... or the week after that. Basics will be revealed, sure. But plenty will also be held back.
So the intrigue will keep building, which will only give the Eagles, as Kelly sees it, more to ignore.
"We don't pay attention to anything, honestly," Kelly said. "I learned that a long time ago. And I've said it before -- I'm glad it's not my quote -- but praise and blame is all the same. If you get caught up in what other people's expectations are, other people's curiosities are, you're short-changing yourself. And if you listen to what other people say, you don't value your own opinion.
"If they're saying good things, and it's, 'Hey, I'm gonna listen to those guys because they're saying really good things about what they think we're gonna do,' and then, 'These people say really bad things about what they think we can do,' you get into mental gymnastics. I'm not smart enough to have those two thoughts at the same time. I just know we gotta work. It's the best athletes in the world, the best coaches in the world; it's the highest level of this game, so don't get caught up in the outside stuff."
One thing that's obvious both inside and outside the Eagles organization is that, as part of a process that'll continue Friday, there are plenty of jobs up for grabs.
Most prominent among them, of course, is the quarterback post. And say this for Kelly: He's not playing favorites. It's nearly impossible to decipher whether Michael Vick or Nick Foles is ahead, at least when it comes to counting reps or ascertaining who's spending more time with the first team, because things are just about dead even in those categories.
Asked what he hopes to see from his signal-callers against New England, Kelly smiled and shot back, "Hopefully, a ton of touchdowns." The way he looks at it, this is just another step, with the coaches getting to evaluate both guys in a new context.
"It'll be how they react in a hot-water situation," Kelly said. "When someone comes clean on a blitz out here (in practice), you blow the whistle. When someone comes clean on Friday night, I don't have a whistle. I wish I did sometimes, but you don't have a whistle. It's gonna be different for a quarterback. And I don't care who you are, there's no quarterback getting hit by their own team. So it's different for everyone."
Vick will start, then alternate series with Foles. The goal is to get each quarterback a certain number of reps before they give way to Matt Barkley, who will play in the second and third quarters. That initial order will be reversed next week against the Carolina Panthers, with Foles starting and Vick subsequently alternating in.
Gbajabiamila: Forgive and forget?
After that, it'd be logical for Kelly to make a call. The third preseason game is traditionally a dress rehearsal, with the preceding week of practices closed to the media/public. And the following week, prep for the regular-season opener starts in earnest.
The thing is, Kelly's way of thinking, as has been documented, doesn't always line up with conventional wisdom.
"By setting a timetable, I think you handcuff yourself," Kelly insisted Wednesday afternoon, emphasizing that someone will have to seize the job.
Kelly also swiftly shot down two ideas: 1) the thought that a two-quarterback system could be an option; and 2) the assumption that the offense will look markedly different depending on which QB is at the controls.
"That's not fair to say," Kelly said. "I don't know. Right now, we're not doing a ton of game-plan things. When you're in a preseason game, there's an evaluation process that has to go on, too. It's, 'Hey, I need to get a couple balls to this guy,' where in a game you might keep feeding this other guy, because of coverage. And it's not drastically different with either guy in there; they both can run what we're gonna do offensively."
The quarterback competition, of course, represents just one of the personnel calls Kelly has coming down the pike in the next three weeks. How those in the front seven fit into the Eagles' new 3-4 defense is still an open question; the secondary remains muddled; and the receiver situation has been shaken up by injury and the words of Riley Cooper, who has otherwise had a strong few months on the field.
There are also plenty of surprises to come, surely. Most of those will stay under wraps for the time being.
Meanwhile, on the flip side, Kelly is now entrenched in his new role as an NFL coach after spending the first 23 years of his career in the college ranks. He says that he was a little surprised to see that, over the course of the offseason, he was actually allotted less time with his players than he had in Eugene, but very little else has caught him off-guard.
That would seem to indicate the coach was ready for all this, but he stopped short of that, too.
"I didn't say that; I just said I'm not surprised," he said. "I never look at anything as a surprise. No matter whether you're in high school or college or the pros, every day brings a new experience to you. You've gotta embrace it and work with it. The people that have preconceived notions -- I think this is gonna happen and that's gonna happen -- you'll probably end up disappointed."
So rather than forecast the future, he'll implement his plan and let things play out.
And there are plenty of us, inside and outside NFL locker rooms, who can't wait to see what happens.