PHILADELPHIA -- A little over a week ago, Washington Redskins Coach Joe Gibbs fixed an ailing offense like a master mechanic fixes a car. Gibbs yanked struggling quarterback Stan Humphries and inserted Jeff Rutledge, as if he were replacing a bad spark plug.

Immediately, Washington's offensive machine was back on the road, humming along to 27 second-half points and a come-from-behind, 41-38 overtime win against Detroit.

While the accolades went to Rutledge, a career backup quarterback who had a Cinderella game, the real credit could just as easily have gone to Gibbs's system, which allowed a player who hadn't started a game in nearly three years to perform so well.

Gibbs's offense is based on progressive quarterback reads, either side-to-side or deep-to-shallow, and creating mismatches by putting offensive players in motion. The approach is hardly revolutionary but it's certainly been effective.

All of which prompts the question: Which is more important, the system or the quarterback running the system?

According to Green Bay Coach Lindy Infante, the ideal situation is to field an offense in which the system and the player meld to create a whole greater than its parts.

In Philadelphia last year, Eagles Coach Buddy Ryan made a committment to run the ball more. Even though the Eagles averaged just four more running plays a game in 1989 than they had in '88, the impact of the more conservative system was profound.

The Eagles' attack bogged down, scoring was off, and Pro Bowl quarterback Randall Cunningham infrequently performed the spontaneous magic that had become his trademark. Even this season, with new offensive coordinator Rich Kotite putting in a system that stressed pre-snap movement, progressive coverage reads, precise depth of receivers' routes and more use of the wideouts, Cunningham was ill at ease at first.

"It's a hand-in-glove thing," Infante said. "You can take a good quarterback, put him in a poor system and he can't help much. Take that same guy, put him in a good system and he becomes outstanding.

"But assuming that most systems are viable -- and they are -- and you had to choose between a good quarterback and a good system that may not be compatible, I think you take the good quarterback and try to figure out what he can do regardless of how good you think your system is."

Rutledge's fabulous performance (completing 30 of 42 for 363 yards and one touchdown) against the Lions in his first appearance as a Redskin was representative of the success Gibbs's system has produced using a variety of quarterbacks with a spectrum of skills. The Washington coach has won Super Bowls with quarterbacks as diverse as the scrambling Joe Theismann and the cast-in-concrete, strong-armed Doug Williams.

Before the Eagles played the Los Angeles Rams in Anaheim, Calif., in the third game of the season, Ryan and Kotite told Cunningham to make things happen. If that involved the quarterback's tucking the ball under his arm and taking off, so be it. And Cunningham has since been on a pace to set personal bests in just about every meaningful offensive category -- passing and running.

"Early in the year, {Cunningham} was kind of waiting," Ryan said. "Maybe waiting a little too long and giving {defenders} a chance to recover."

"If you have a guy like Cunningham, who's a great study in this case, there's going to be certain things that he can do that you're going to make a part of your system -- things that we can't even consider," Gibbs said. "But not only a quarterback can change your system; a running back can too. We've had John Riggins here, who was an inside gut guy and not much of a sweep runner. With that guy, you didn't pitch the ball. You handed off and let him do what he does best. Now, we've got an Earnest Byner, who is a little more versatile. He can play halfback and catches the ball well. Those people dictate your system and you have to adjust."

That the Eagles needed a system that would make Cunningham a more well-rounded quarterback was a case of responding to enemy tactics.

"You know, all I heard before I got here was that to stop Randall all you had to do was keep him in the pocket," Kotite said. "Well, that's not true anymore. You keep Cunningham in the pocket now and give him a little time, and he'll knock your eyes out."