The unwritten rule that NFL players can't lose their starting jobs due to injury obviously does not apply in Philadelphia, especially for Eagles quarterbacks.

Michael Vick supplanted Kevin Kolb with electrifying play while the latter sat out with a concussion. Last year, an efficient Nick Foles took over for Vick while he was sidelined. Could Foles be next on the list of bounced Philly QBs?

The 25-year-old will miss the next six to eight weeks with a broken collar bone. However, Foles may have been on his way out of Philadelphia long before the injury.

"I think [general manager] Howie [Roseman] is looking at quarterbacks," an unnamed NFL source told NJ.com's Mark Eckel. "He's kind of soured on Foles, and I don't think he's alone. The organization isn't sold that he's the guy going forward."

That would explain why coach Chip Kelly gave Foles an, at best, lukewarm endorsement as the team's quarterback in December of last year.

"Yeah, you hope," Kelly said at the time when asked if Foles was Philadelphia's quarterback of the future. "But - and I don't mean to be coy, I always say this - is that, you can say that whomever it is, is your player of the future and then next week they get hurt."

There is considerable speculation around the league that the Eagles will try desperately to trade up in the draft to select Oregon Ducks' quarterback and former Kelly pupil, Marcus Mariota.

Foles threw 28 touchdowns against just two interceptions last season, including a seven touchdown game against the Oakland Raiders. This season, however, he has thrown 13 touchdowns and 10 interceptions while losing three fumbles. He is completing a career low of 59 percent of his passes.

Mark Sanchez took over after Foles' injury and led the Eagles to a 31-21 victory over the Houston Texans. But Sanchez's propensity for turnovers makes it unlikely that the Eagles have their quarterback of the future currently on the roster.