PHILADELPHIA (973espn.com) — If you remember John Facenda sending chills up and down your spine by waxing poetic about the frozen tundra you probably can also think back and picture the "Voice of God" narrating over the highlights of a short guy running around in a purple No. 10 jersey.

Fran Tarkenton was the best scrambling quarterback in NFL history, at least until the game evolved into what it is in the modern era and the former Minnesota Vikings' superstar is the first name that popped into Jim Schwartz's head when asked about current Seattle signal caller Russell Wilson.

"I've compared him in the past to Fran Tarkenton," the Eagles' defensive coordinator said Tuesday.

Wilson is as unique as they come, the rare quarterback that can extend plays not only by moving from side to side or manipulating himself in the pocket but by also moving backward, typically a no-no for just about anyone not named Tarkenton or Wilson.

"Probably the thing that Wilson is most dangerous in is threatening by running backwards," Schwartz explained. "It's easy to keep containment. You can keep contain, and you can prevent step-ups. It's hard to get somebody directly behind the quarterback, and that's where he can really just turn and run and escape. Once he does, that creates problems for your whole defense."

It remains to be seen if Wilson joins Tarkenton in Canton one day but the Seahawks quarterback is off to a Hall of Fame start in his career, already winning one Super Bowl and coming up a yard short of another turning Seattle into a perennial playoff team along the way since the organization stole him in the third round of the 2012 NFL Draft.

Wilson also represents a sharp step up in class from the quarterbacks the 10-1 Eagles have faced over the past month in which they've dominated.

Instead of C.J. Beathard, Brock Osweiler, Mitchell Trubisky and even a struggling Dak Prescott, Philadelphia will face a magician on the road in perhaps the toughest environment to play in the NFL has, Seattle's CenturyLink Field.

"Russell threatens the whole field," Schwartz said. "He'll boot one-way and throw back the other. You have to stay alive on everything. Our defensive linemen are going to have to stay alive and on their feet. You can never go to sleep. If he's scrambling one way, there's a good chance that he's coming back to you. We have to stay alive in coverage, as well as our rush. Russell threatens the whole length and the whole width of the field."

And there's nobody else like him unless you want to visit the wayback machine and find Tarkenton.

"Russell Wilson is unique in his own ways," Schwartz insisted. "He can run the designed quarterback runs; the zone reads and keepers. He can also just create something off schedule."

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen

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