It's buoyed by the ability of one to handle the success of the other, and vice versa.
Perhaps the most missed aspect of Andy Reid's signal-caller shuffle lies therein -- neither player is threatened by the presence of the other. And that's not common, not in a high-stakes position battle, not in a high-pressure place like Philadelphia, not with a roster stocked with impressionable young players lacking past experience to draw on.
You better believe that if Donovan McNabb was still around, such an arrangement wouldn't work, nor would it fly with almost any situation with an entrenched, franchise-type starter. That's why this story is unique.
The Eagles have two honest-to-God starting quarterbacks. Vick's the starter. Kolb's a starter. Could it flip? Sure, and that's the beauty of the arrangement.
"We can compete and be friends at the same time," Vick said, walking from the locker room to the bus at LP Field in Nashville on Sunday, moments after Reid informed the masses that he was going to be the starter coming off Philadelphia's bye. "And it's not like you're competing against a guy you don't have a relationship with or can't talk to, that puts more pressure on the situation.
"Naturally, we've developed a friendship. We like fishing, we like a lot of the same things, we roomed together in camp, and we had a great offseason together. We're just rooting for one another."
The idea that it was risky for the Eagles to pick up Vick's $5.2 million option for 2010 now seems silly. The two-year, $12.25 million contract afforded to Kolb, even if he's the backup the rest of the year, is a relative bargain for a 26-year-old who's long been considered a cornerstone of Philadelphia's future.
Eventually, the Eagles will have to pay one and move on from the other, but for now, an investment of $17.45 million gets them a combined three seasons of Kolb and Vick. By comparison, Philadelphia committed $24.5 million over two years to Donovan McNabb alone in 2009, prior to trading him to Washington in April.
Despite their more limited playing time, Kolb and Vick have six touchdown passes apiece, as many as McNabb, and each Eagles quarterback has fewer picks and a higher passer rating than their predecessor. McNabb said in the aftermath of Washington's big win in Philadelphia in Week 4 that the Eagles made a mistake trading him. It's harder to say that now, particularly because of the way each guy is treading smoothly through the kind of waters that generally get choppy.
"It hasn't been that bad. The only tough thing about it is everybody makes a big deal out of it," second-year tailback LeSean McCoy said. "We have two great quarterbacks that can start pretty much anywhere; we have two stars on the same team. Kevin's very, very talented, as you can see. And Mike is ... Mike is Michael Vick. You know what I mean? But other than that, guys come in the same way, prepare the same way, it's not really a big difference when one plays and the other doesn't."
Under much scrutiny coming out of that loss to the Redskins, Kolb exhibited the steely demeanor that the Eagles loved about him all along in putting together consecutive big performances against the 49ers and Falcons. They'll look for Vick to handle himself similarly against the Colts in Week 9 coming out of the bye, and then Washington again.
One thing's for sure: This isn't splitting the team the way some quarterback competitions over the course of football history have. Tight end Brent Celek told me last week that he'd never have believed a two-quarterback system could work on the NFL level, before he saw these two work together. Offensive coordinator Marty Morhinweg wasn't all that enthusiastic about the idea, but sees what Celek's saying.
"Anything could work, but do you want something like that and all those type of things?" Morhinweg said. "Look, both of them, I think, are excellent quarterbacks. Both of them have a great future. Mike is sort of getting his re-start, and then Kevin's getting his start.
"And Kevin's going to have his ups and downs, and I thought he battled through real well (on Sunday). I think both have bright, bright futures in this league."
The team's confidence in Kolb has been well-documented. The club wouldn't have dealt an 11-year staple like McNabb if it didn't feel strongly about him.
As for Vick, Mornhinweg echoed McCoy's words -- "Mike is Michael Vick" -- comparing him to another athletic lefty he coached. That's Steve Young. Morhinweg has, in fact, shown Vick volumes of tape of the 49ers legend. "Mike's got a long way to go to get to where Steve Young wound up, one of the great passers in the history of the game, one of the most accurate passers in the history of the game," Mornhinweg said. "But Mike's working diligently to become like that, and he's certainly got the skill and ability to do that."
Taking all of this into account, the Eagles are detonating the old adage that if you have two starting quarterbacks you really have none.
Both these guys, clearly, can play. But what really has made it work is the personality of each guy.
Each has plenty invested here. For Kolb, it's the four years of development in the Eagles offense, and the chance to remain in Philadelphia long-term. For Vick, it's reviving his career and completing a comeback from a jail sentence that, no matter how you feel about his prior transgression, is very remarkable.
Yet, these fishing and golfing buddies are able to handle it, thrive individually, and keep the shuffle from splitting the locker room or hurting the club's prospects too much. That reflects pretty well on them.
"It's all genuine, and I wouldn't believe that if I wasn't a part of it," Celek said. "You've seen what they've both done, the stats show that they're two of the best, and they're on the same team. Having that, we're not having a hard time at all with it. They're playing their butts off, making plays left and right, and we're winning games."
And that says more for Vick and Kolb, as people and teammates, than their physical ability ever could.