What is Kevin Kolb worth?

Kevin Kolb's value is in question on the trade market. Jason O. Watson/US Presswire

"Kolb can play. He is very, very accurate. I compare him to Tom Brady. ... He, like Brady, is a great leader." -- Eagles DE Trent Cole to NFL Radio, last week

Quarterback history in the NFL can be like those choose-your-own-adventure books you had as a kid -- only read in reverse. Try this one: In the spring of 2004, the Eagles were blessed with quarterback depth. They had a good starter, and their backup had been used the year before, going 4-1 and leading the team to the playoffs. The backup was a hot commodity, and the Eagles knew it. They traded him to the Miami Dolphins for a second-round pick. The Dolphins owner at the time said the new man could be "another Dan Marino." A.J. Feeley, as it turns out, was not Dan Marino. Benched after eight starts in Miami, Feeley has started two NFL games since. It happens.

That same spring, Matt Schaub was drafted to back up Michael Vick in Atlanta. After three years of relative inaction behind a successful Vick, Schaub was dealt to Houston, like Feeley, for a second-round pick. Schaub flourished. That also happens.

Fast forward to Philly last year: Vick again emerged, and again with quarterback depth, the Eagles traded away the same quarterback who once made Feeley expendable. Donovan McNabb was dealt to Washington in a trade built around, yes, a second-round pick. And because McNabb is gone, and Vick is back, well ...

... here sits Kevin Kolb, the current Eagles backup quarterback, the next Schaub. He's been rumored to a third of the teams in the league, and during the draft there was significant talk that if it was possible at the time, Arizona's No. 5 pick could grease a deal to send him to Glendale. But what is Kolb? Is he more than a hunch?