PHILADELPHIA — R.J. Umberger did all he could to keep his scoreless streak from overwhelming his confidence.
Umberger got his first goal since Jan. 27, 2015.
"It became a mental challenge. It can get the best of you," Umberger said. "You start to question yourself, but deep down I know what kind of player I can be. I know I can add to the team."
Brayden Schenn, Michael Raffl and Nick Cousins also scored for Philadelphia, which scored four goals during a dominant second period.
Philadelphia needs every point it can get to stay in the playoff race — the Flyers began play five points out of a postseason spot and behind five teams.
"It's huge for us, everyone pulling on the same side of the rope, having an explosion like that," said Flyers rookie defenseman Shayne Gostisbehere, who tied a club rookie record by extending his point streak to 10 games.
Jamie McGinn scored for Buffalo, and the Sabres lost their fourth in a row while wrapping up a three-game season series against the Flyers with their first loss.
Steve Mason had 41 saves while making his sixth straight start for Philadelphia.
Gostisbehere had an assist to tie Mikael Renberg's Flyers rookie record set in the 1993-94 season. It's also the longest current streak in the NHL.
Umberger put the Flyers on the board 1:23 into the second period. He took a nice feed from Sam Gagner and beat Robin Lehner over the right pad. He had been a healthy scratch the last five games but replaced Matt Read in coach Dave Hakstol's lineup after Philadelphia's lackluster performance in a 4-1 home loss Tuesday night to Anaheim.
"Not a lot of things have bounced his way," Hakstol said. "Everybody was fired up for him."
The goal was the 179th of Umberger's career.
After scoring, Umberger thrust both arms in the air and looked skyward before being mobbed by teammates. He then blessed himself and let out a huge smile while being congratulated along the Flyers bench.
"It was a little prayer to the hockey gods: thank you," he said.
Umberger's goal opened the floodgates. Schenn followed 48 seconds later with his 15th of the season on a one-timer from close range. Simmonds then got his 10th goal in the last 13 games while reaching 20 goals for the third straight season with a wrist shot that beat Lehner on the short side. Raffl finished the second-period barrage with 4:03 left, with Cousins earning his second career point with an assist. Cousins later got his first career goal.
Buffalo allowed four goals to open things for the second straight game after doing it in a 7-4 home defeat to Florida on Tuesday night.
"Mental breakdowns, turnovers, lack of coverage, it's a little bit of everything," captain Brian Gionta said.
Philadelphia's Radko Gudas was involved in two fights. The second came with 3:33 left in the game after Buffalo's Jake McCabe retaliated following Gudas' hard check of Daniel Catenacci, who had his head down when he was leveled at center ice.
Sabres coach Dan Bylsma said after the game that Catenacci was going through concussion testing. Both Bylsma and his players were upset with Gudas.
"He's an idiot," said Marcus Foligno, who fought Gudas in the second period after being leg whipped. "He gets his hits in and is dirty and has been known for it. Goes after a rookie who's been in three games and gets right at his head. Wish (I) was on ice and could've done more damage to him."
Bylsma expects the league to look into a possible suspension.
Lehner stopped 23 of 28 shots.
Notes: RW Justin Bailey made his NHL debut and had seven shots for the Sabres. The 2013 second-round pick had 10 goals and 23 points in 47 games with Rochester in the AHL. "I thought he was probably our best player tonight in the game," Bylsma said. ... The Sabres' last season sweep of Philadelphia came in 2001-02 when they went 4-0. ... Buffalo C Ryan O'Reilly leads the Sabres with 17 goals but has gone 14 straight games without a goal. ... Buffalo beat the Flyers 4-3 in overtime on Oct. 27 and 3-1 on Oct. 30. ... Buffalo went 0 for 6 on the power play.