Eagles' defenders know even when Ben Roethlisberger appears to be in trouble he can still make a big play. (US Presswire)

The Philadelphia Eagles’ Michael Vick and the Pittsburgh Steelers’ Ben Roethlisberger excel at getting out of the pocket and extending plays.

But there is one major difference between these two super quarterbacks -- Vick flies away from defensive players and Roethlisberger simply lets them bounce off his chest.

“He’s about 260, 270 pounds, so arm tackles are not going to tackle him in the pocket,’’ said Eagles LB Jamar Chaney, who apparently doesn’t believe the Steelers roster sheet that officially lists Roethlisberger at 241 pounds.

“And grabbing one leg or something like that won’t work against him either," Chaney added, "or sacking the quarterback with one arm. With most quarterbacks you probably can do that, but with him you can’t.’’

Roethlisberger isn’t the elusive open-field runner that Vick is, but he is an effective scrambler with the ability to avoid the pass rush and then throw downfield for a big play.

That’s why the Eagles coaches have reminded their defensive backs and linebackers to stick with their coverage even if they see Roethlisberger start to run.

In fact, the Eagles' defense has even practiced this week what it calls its "scramble drill,'' where players focus on maintaining their coverage no matter what.

“He may scramble and he may get eight or nine or five or 10 (yards),’’ Eagles defensive coordinator Juan Castillo said. “But if you come off your guy, that could be a touchdown.”

For more up-to-the-minute news and analysis on the Philadelphia Eagles from blogger Kevin Noonan, follow @CBSEagles.