I've been in Philly since 1994, and I can't count the number of times Eagles fans have told me how a game against Dallas can make or break a season for them.
A good season can get a sour taste if the Birds take an unexpected loss to Dallas. A bad season can always have a silver lining if there is at least one mark in the "W" column against the Cowboys.
I've never fully believed it, but I've had more than a few Eagles fans tell me they'd rather beat Dallas twice in a season than make the playoffs.
The general logic seems to be if the Birds can't win the Super Bowl, at least beat Dallas. That will always give some measure of satisfaction.
Games against the Cowboys can change a coach's fortunes in Philadelphia, as far as fan support.
In Philadelphia, Dick Vermeil pumped Dallas hatred when he was rebuilding a franchise that was coming off nine consecutive non-winning seasons.
After losing his first six encounters with the Cowboys, Vermeil finally beat Dallas on Nov. 12, 1979, at Texas Stadium.
But it was the 1980 season that truly ignited Philadelphia's hatred of Dallas. The Eagles split their regular-season games with the Cowboys but won the NFC East, their first division title in 2 decades.
However, even though the Birds were hosting Dallas in the NFC Championship Game at Veterans Stadium, Las Vegas installed the Cowboys as a favorite.
Vermeil took great umbrage to that.
"Never allow anyone to take you for granted," Vermeil snorted. "I get the feeling the Dallas Cowboys are taking us for granted right now.
"We're here because we earned the right to be here. If the Dallas Cowboys are going to take us for granted, we'll whip their ass."
That was straight Philly attitude. It turned to reality when the Eagles beat the 'Boys, 20-7, to advance to Super Bowl XV in a game still remembered by a generation of fans as the greatest victory ever witnessed.
Buddy Ryan never won a playoff game with the Eagles, but he forever won the heart of Philadelphia in large part because he understood the significance of beating Dallas.
Ryan went 8-2 against the Cowboys, with victories often coming in colorful fashion.
When I came to Philly, the Eagles were transitioning from the Norman Braman era to new owner Jeffrey Lurie.
Dallas was finishing out a string of dominance with three Super Bowl wins in four seasons.
It was not a pleasant time for Eagles fans, but even hated head coach Rich Kotite would get some hometown love when he managed to beat the Cowboys. Unfortunately, he only did it twice in eight regular-season meetings. He also lost a playoff game to Dallas.
Like Ryan, Lurie's first handpicked coach, Ray Rhodes, knew the first step into the heart of Philadelphia was beating Dallas.
Ray Bob made the playoffs in his first season, but his biggest accomplishment was beating Dallas, 20-17, at Veterans Stadium. Of course, that was blemished when the Birds got crushed, 30-11, in the playoffs at Dallas.
Rhodes split with Dallas in his first three seasons but got swept in his final year to finish with a 3-5 overall record.
Andy Reid, whose hiring was the subject of much debate in 1999, got off to a 0-4 start, but he bought a lot of grace from skeptical fans when his first win was over Dallas, 13-10.
From 1999 through 2004, when Reid had the Eagles challenging for Super Bowls, he went 10-2 against Dallas, including a six-game winning streak.
Ironically, the ultimate decline of the Reid era can be traced to the conclusion of the 2009 season, when the Eagles lost 24-0 at Dallas, costing them the NFC East title and the home field in the wild-card rematch the following week. The Birds returned to Dallas; Donovan McNabb played air guitar during introduction; the Birds got stomped, 34-14; and a great era of Eagles football effectively ended.
Overall, Reid was 17-11 in regular-season games against Dallas.
I see Kelly as being in a similar position as Reid was in 1999. Kelly had a bigger name coming in because of his successful tenure at the University of Oregon, but he hasn't been completely sold to the entire Eagles fan base.
While it may not be fair, Kelly is still saddled with the college-to-NFL albatross. Some in Eagles nation are actively looking for flaws that will justify their thoughts that he is bound to run back to the NCAA at his first opportunity.
But if the Eagles beat Dallas on Sunday, end their eight-game losing streak at Lincoln Financial Field and strut into first place, Kelly will likely get just about everyone on board for his rebuilding program.
That is the potential power of Dallas Week for an Eagles coach.