"It is a massive matchup in terms of Pennsylvania ego," Roenick, who played for the Flyers from 2001-04, told NHL.com. "These fans don't like each other. It's amazing to be in one state and have fans on each side dislike each other as much as they do."
To Roenick, the fans can play a role in the outcome of the game in each city with their emotion and noise. That's why the winner of the game Sunday in Pittsburgh (12:30 p.m. ET, NBC) could have a huge advantage come playoff time.
The Penguins and Flyers are locked in a battle for the fourth seed, which includes home-ice advantage in the first round. The Penguins had a four-point lead entering Saturday thanks to their 5-3 win against Buffalo on Friday, but the Flyers were playing Ottawa on Saturday afternoon.
Roenick said if the Flyers and Penguins meet in the first round, he'd pick the team had the home-ice advantage.
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"If you're going to play a team like Pittsburgh in the first round, home-ice advantage becomes so critical. That might be the Flyers mentality right now."
What about the Penguins, who lost to the Islanders twice this week by 5-3 scores before beating the Sabres in Buffalo by the same count?
Roenick said Pittsburgh's defensive structure was bad against the Isles, and it could be a result of overconfidence on the offensive side since Sidney Crosby returned to the lineup March 15.
The Penguins have scored 45 goals in the 10 games since Crosby came back, but they've given up 35, including eight in a blowout loss to Ottawa and the 10 over two games against the Islanders. They've played the last three games without All-Star defenseman Kris Letang, who Roenick called "one of the more important defenseman in the NHL to his team."
Letang is questionable for Sunday.
"They've had a lot of confidence when they go on the offensive, but it's almost like they've taken their defensive structure and gone free-wheeling, for lack of a better word," Roenick said of the Penguins. "To lose 5-3 to the Islanders twice in one week … I mean, really? They might be a little bit overconfident right now with having so much talent offensively. I would expect that coach (Dan) Bylsma is going to step on these guys and make them realize they were winning games because of their style, structure and defense, not because of what they can do offensively.
"If they can put it all together, I don't know who can beat them in the playoffs."
Well, the Flyers can, according to Roenick, if they get home-ice advantage in the first round.
They can move closer to that with a win Sunday in Pittsburgh.
"The Flyers will try to put a Broad Street pounding on them," Roenick said. "If it happens, it might be the best first round matchup of the playoffs, not only talent-wise, but physically, mentally and geographically. It's great for TV. It'd be great for NBC to carry such a great rivalry in the first round."
Follow Dan Rosen on Twitter at: @drosennhl