After watching their defense allow 56 points in a loss to Louisville Sept. 23, Boston College head football coach Jeff Hafley and defensive line coach Vince Oghobaase decided it was time to let their players loose.

They made the choice to have the linemen take more risks, be more aggressive, and play with more of a strike-first mentality. The result was a breakout six-sack performance — for a defense that had just four total going in — in last Saturday’s 27-24 win over Virginia.

“We had a long talk,” defensive end Donovan Ezeiruaku said. “We looked ourselves in the mirror. We’ve got to do something. We’ve got to change. The defense, we took ownership of that loss last week and letting up all those explosives like we did.”

The Eagles allowed just 39 second-half yards against the Cavaliers. They controlled the line of scrimmage, won one-on-one battles, and played fearless football.

They’ll keep that same mind-set this Saturday for a noon matchup at Army, but the specifics will change slightly based on the opponent.

The Eagles (2-3) know the Black Knights (2-2) like to run the ball and mix in pass plays to keep the defense honest. They believe that if they play with the same edge — while scaling it back as needed against a mobile quarterback — the results will take care of themselves.

“It’s feeding off of each other’s energy,” defensive lineman George Rooks said. “We preach synergy. We did that last week, and we’re going to keep doing that moving forward.”

Army has the No. 14 rushing offense (208 yards per game) and the 164th-ranked passing attack (169.5) in the nation. Hafley said the offense has a triple-option element and a flexbone element but features more shotgun than wishbone. He said it’s “very different and challenging,” and the Black Knights will try to trick the opponent with their eyes.

Hafley said staying disciplined is particularly key, especially against a dual-threat quarterback in Bryson Daily who can take off at any moment. Army also has a 255-pound running back in Jakobi Buchanan.

BC linebacker Vinny DePalma said the emphasis is on tackling low to “take out the engine” against sizable players.

“It’s going to be a very tough game,” Hafley said. “This team plays very hard, they’re very physical, and the style of game that it’s going to be, it might be the most physical one we have all year.”

Rooks, a 6-foot-4-inch, 280-pound transfer from Michigan, figures to play a key role again. He totaled a season-high five tackles, one quarterback hit, 1.5 tackles for loss, and 1.5 sacks for 10 yards against the Cavaliers.

Hafley credited him for being a “quick-twitch” player who’s starting to learn how to play within the scheme. He called him an “instinctive guy” who’s using his speed to his advantage and getting great pressure on the quarterback. He played as critical a role as anyone in spearheading the comeback against Virginia.

“I think we were all feeding off each other,” Rooks said. “After [Ezeiruaku’s] first sack, we were all competing: Who’s going to get the next one?”

The comeback was commendable, but at the same time, the Eagles wish they never needed to rally. Their start wasn’t nearly as ghastly as it was against Louisville — BC allowed touchdowns on the Cardinals’ first seven drives — but the overall concept holds true.

Against a particularly methodical opponent, BC has to ensure Army doesn’t use tons of clock on its opening drive, score, get a stop, and do it all over again.

Opponents have outscored BC, 21-0, in the first quarter of the past two games. Army, meanwhile, has outscored its opponents, 36-0, in the first quarter this season. The Eagles know they can’t beat themselves early or ease into the game against an opponent as relentless as this one.

“This is a game on offense where you have to be really efficient, because you don’t know how many possessions you’re going to get,” Hafley said.

…

Wide receiver Ryan O’Keefe, who suffered a neck injury in the fourth quarter against Virginia, returned to campus Sunday after being discharged from Massachusetts General Hospital.

Hafley said O’Keefe is “on the road to recovery” and that it was great to have him as a spectator at practice. There’s no timetable for his return, but Hafley is “hopeful to get him back” whenever it’s safe for him to play.

“It’s scary,” said O’Keefe’s roommate, offensive lineman Kyle Hergel. “You never know when it’s your last play, but at the same time, he had a good mentality about it. He wanted us to go finish the job and get the win. That was one of the first things he asked me in the hospital. He knew we won, but he wanted to know how it went.”