Dr. Joel Fish analyzed the patient stretched out before him.

"It's been a confusing time" for the psyche, Fish empathized. "Are we the favorites or are we the underdogs? Are we optimistic or are we pessimistic?"

As the Eagles make NFL history as the first team to be both a No. 1 seed and the underdog heading into Saturday's playoff game against the Atlanta Falcons, we on the collective Quaker City couch are feeling the whiplash.

We were making such progress, lamented Fish, a lifelong Philadelphian who heads the Center for Sport Psychology. "We became comfortable, as time went on, allowing ourselves to dream. We started to buy into the fact this could be a really special year, and that was so good for our growth," Fish said. "And then –."

And then quarterback Carson Wentz tore his ACL and hearts sank into the Delaware Valley. High hopes came crashing down.

"This is totally something that would happen to Philadelphia," said @ZooWithRoy, a Philly sports guru and Twitter personality. "Even when things were going well, I had this foreboding sense of doom, because we don't just lose, we lose spectacularly. But at the same time, I watch every week and I get excited, and I've already talked myself into how we're going to win on Saturday."

That's the Philly sports fan's dual psyche, Fish said. We are conditioned to expect the worst, and boo the home team out of fear and frustration. We assume that even the sunniest situations will end badly. At the same time, the city of Rocky rallies as one when written off or underestimated. And being the long shot means being in our comfort zone.

"Philly is an underdog city," said Vince Papale, perhaps the city's most famous real-life sports long shot. Papale, who walked onto the Eagles' special teams in 1976, was nicknamed "Rocky" during his career with the team and inspired the movie Invincible.

"Rocky was the ultimate fictional underdog, and with me, fiction became reality and the impossible became possible," Papale said. "I think Philly is the perfect town to embrace someone like that. I was that guy that put the pads and helmet on for the lunch-pail guys and the guys in the nosebleeds."

The one-time 30-year-old NFL rookie is now 71, living in Cherry Hill, and working as a motivational speaker. He'll be at Lincoln Financial Field on Saturday with his family. The last game Papale played with the Eagles was against the Falcons in the 1978 NFL wild card game. The Eagles lost, 14-13. ("We missed the field goal at the end of the game," he said. "That was brutal.")

Yet in the next breath, Papale went on about how he's angered by the way the Eagles' postseason chances have been so readily discounted. After seeing the Las Vegas line had the Eagles as the 2.5-point losers, Papale posted on Facebook about the power of the underdog: "It drove me to prove the doubters wrong and to get the last laugh. … Who's Nuts Baby! Fly Eagles Fly."

Eagles defensive tackle Fletcher Cox seemed to channel that attitude when he told reporters this week, "It just puts a bigger chip on our shoulder and just adds fuel to the fire, and that's what this team, obviously, has been going off of all year."

The ultimate test for fans, Fish says, is what they do Saturday if the team flounders early. Will they stay hopeful (tapping into the relentless Rocky optimism) or will they start to boo (letting the fatalistic side of their psyche take over)?

"We have three or four generations of fans with an oral tradition of being disappointed," Fish said. "And if you're a younger fan in your 20s, you've spent a lot of time, like my three kids, listening to us watch and wait for the other shoe to drop."

This has been the local attitude since we wore tricorn hats. The late sociologist and University of Pennsylvania professor E. Digby Baltzell wrote that "cheering against the home team is a time-honored tradition in Philadelphia." Self-deprecation, he once told an Inquirer reporter, "is very deeply rooted in the Philadelphia mores, at all levels of society."

Bruce Graham, who wrote the play The Philly Fan about our collective sports psyche, traces the city's testy attitude to 1800.

"I think ever since they took the nation's capital away from us, we've been kind of pissed off," Graham said. "I think our image in the rest of the country is better, but when it comes to our attitude about ourselves, we do kind of relish our underdog status. … Even when we're the favorite, we're the underdog."

That, of course, can be overrated, @ZooWithRoy said. While it makes for fun stories, "the thing is, they usually lose."

@ZooWithRoy said he's glad the game is Saturday and not Sunday so he has time to recover in case of defeat. The day after the Eagles lost the Super Bowl in 2004, he got into a car accident while listening to sports talk radio on the drive to work.

"The woman I hit got out of the car and said, 'First the Eagles lose, now this,' " he said. "I was so happy to have someone to commiserate with."