From his bedroom in Tucson, Ariz., Nick Foles paid little attention to Michael Vick's unseating Kevin Kolb as the Eagles starting quarterback in 2010. When Arizona's junior quarterback unwound in front of the television, he eschewed SportsCenter for scripted dramas.

What happened in Philadelphia was of the unscripted variety.

Andy Reid said Kolb's job was not in question after an injury and maintained that position until an unanticipated about-face. Injury opened the door, and the backup's performance was too convincing to ignore.

It landed Tom Brady the starting job in New England in 2001. It made Colin Kaepernick the starter in San Francisco last season. And it might just turn Foles into the Eagles starter this season.

Vick, who beat out Foles for the starting job during the summer, will miss his second consecutive game with a pulled left hamstring. Foles will start in his place Sunday against the Dallas Cowboys. Two starts was all Vick needed in 2010 to persuade Andy Reid to keep him as the No. 1 quarterback.

"I didn't think I was going to be the starter for the rest of the season," Vick said this past week. "Me and [Kolb] made the most of it. Me and [Kolb] are still great friends to this day. We all had a lot of success along the way. That's what it's all about."

If that's what it's all about, then Sunday's game could have reverberations for both Vick and Foles. Another sterling performance by Foles would give the Eagles three consecutive wins and offer convincing evidence for Chip Kelly to keep Foles in the No. 1 spot even when Vick's healthy.

Kelly has been mum on what will happen. His strongest statement came a few hours after Vick's injury in the Oct. 6 win over the Giants, when he said Vick remained his quarterback when healthy.

Kelly has since backtracked and evaded the question, declining to deal with the hypothetical and leaving the door open for a potential change. When asked whether a player should lose his job because of injury, Kelly said: "It all depends on the individual situation."

As an offensive coordinator, Kelly lost starting quarterbacks at New Hampshire in 2004 and Oregon in 2007, but both were season-ending injuries. He now has to navigate the nebulous terrain that coaches deal with when a reserve plays well enough to usurp an established starter whose only fault was suffering an injury.

"You always say you can't lose your job when you're hurt. Well, I don't know who made that rule up," said ESPN analyst Herm Edwards, a former NFL coach who experienced a similar situation in Kansas City. "But I do know this: Winning is probably the most important thing, and if you're winning games and have some momentum going, you don't want to disrupt it."

'We got this going'

The conundrum for coaches is weighing the momentum generated by the reserve with the equity built by the starter. In 2006, Edwards dealt with that debate. Damon Huard went 5-3 replacing Trent Green as Kansas City's starter, and there was discussion about whether he should keep the job when Green returned.

Edwards reinserted Green. He said Green was the starter, Huard was the backup, and it was that way for a reason. Edwards also said the return of the starter can be a jolt to the team, and he felt Huard was wearing down. But he acknowledged the challenge of changing against momentum.

"There lies the rub," Edwards said. "The momentum is always good when you're winning. And the one thing about coaches and players, when you're winning, you want to continue to win. Not saying the other guy can't come in there and win, but it's like, we got this going right now and I don't want to upset it."

That was 49ers coach Jim Harbaugh's public argument last November. Alex Smith was 6-2 as a starter and had brought San Francisco to the NFC championship game the previous season. But a concussion opened a spot for Kaepernick, and the dynamism that Kaepernick displayed in consecutive victories persuaded Harbaugh to stick with his No. 2.

"What tips the scale, Colin has the hot hand, and we're going with Colin," Harbaugh said last November.

Reid's argument was similar in 2010, when he said Vick was "possibly the hottest quarterback" in the NFL and deserved a chance to play.

Winning is too precious to mess with, as Bill Belichick determined in 2001, when he decided to keep the little-known Tom Brady as starter over Pro Bowler Drew Bledsoe. Brady had the Patriots winning when Bledsoe was medically cleared. Three Super Bowl rings later, it proved to be the right decision.

Time is a worthwhile component of the evaluation process, because more snaps reveal whether early success is the norm or an aberration. Edwards pointed out that with accumulated information on a quarterback, a defense can determine new ways to attack. He also said being a backup can conceal blemishes that get exposed with time.

Cowboys coach Jason Garrett was a longtime backup quarterback - he went 3-2 as a starter in 1998 - but he wasn't going to unseat Troy Aikman, who had won three Super Bowls. Norristown native Steve Bono went 5-1 for the 49ers in 1991 replacing Steve Young (who had replaced Joe Montana). Young took the job back only after a Bono injury. Young led the 49ers to a 14-2 record the following season and a Super Bowl in 1995 and had a Hall of Fame career.

Sometimes, there's a reason the starter is the starter.

In situations where the starter won the job in a competition - like the Eagles had this summer - the coach must consider the initial evaluation. Vick won the job in August, and Kelly must determine if what he has watched the last couple of weeks changes what he witnessed over a few months.

"It wasn't by accident," Edwards said of starters winning quarterback competitions. "It was because the other guy beat him out. You got to keep that in mind. And you win sometimes, it covers up those flaws, why he was not the starter. And you can't lose sight of that."

The impact on the team

The quarterback decision also can affect the locker room. It's often not an issue as long as the motivation appears to be winning and not ancillary considerations such as salary or draft status.

"One thing about players: Players want to win," Edwards said. "If Nick Foles is playing well, no player is going to say Mike Vick has to be the guy."

Eagles linebacker DeMeco Ryans was on the Texans in 2007, when Sage Rosenfels went 4-1 in relief of Matt Schaub, who went 4-7. The Texans stuck with Schaub. Ryans said that inside the locker room there is not much debate about a quarterback controversy because the players have no control over it.

"The head coach makes the call for whoever is going to start at quarterback," Ryans said. "That's his call. We can't make that decision. . . . A lot of people were saying Sage should be the quarterback, but we didn't look at it like that as players. We said as a defense, we still got to go do our job. The QB, he does his job. Let's go win this game."

It also helps that Vick and Foles remained supportive of each other. Their joint news conference on Thursday made for good television, but there is genuine admiration between them. Vick remarked earlier in the week that he doesn't need to rush back because of how well Foles is playing, and Foles is deferential whenever he's around Vick.

"When Mike's out there, I love watching him," Foles said. "When he comes to the sideline, I'm going to be there, talking to him. He does the same for me. We can't worry about [a change at starter]. That's what messes up friendships. That's not what it's about. We want to keep this friendship as long as we live."

Foles might sound like he's auditioning for a romantic comedy, but it illustrates the amicability. It's also easier to say it when there's no decision to make. That will change, and potentially next week. Edwards said that if Foles plays as well as he did last week, the Eagles would need to keep him as starter. Talk radio is flooded with callers who agree.

If Foles struggles, Kelly's decision will be easier. Vick's injury might get the Eagles their quarterback of the future, just as an injury did in New England in 2001 and in San Francisco in 2012. Or Foles might merely be a valuable backup keeping Vick's seat warm. The script could be written Sunday.