LOS ANGELES >> Two months before Zach Banner’s signed letter of intent arrived at Heritage Hall, the lobby of the building was filled for a celebration. Fans, song girls and USC’s marching band gathered around a 12-foot Christmas tree to hear from Matt Barkley, the Trojans’ talented quarterback who had been weighing whether to declare for the NFL draft.

Barkley told them he was coming back for his senior season.

It coincided with the football team’s ascension. Though USC was amid NCAA sanctions, it finished 10-2 overall the previous season in 2011 and No. 6 in the final Associated Press pol. USC looked like it was coming back, too.

Banner and other recruits followed, arriving on campus in 2012 and 2013 to play for then-coach Lane Kiffin and hoping to help USC reassert itself as one of the nation’s preeminent programs.

Wins have not followed so easily.

For nine of the 14 seniors who will play in their final game at the Coliseum on Saturday against Notre Dame, their careers have spanned the most turbulent era of USC football.

“No one’s had it crazier than me and my class,” right tackle Banner said.

Their period saw the cratering of Kiffin’s tenure, a respite led by Ed Orgeron, a rocky run with Steve Sarkisian and return to normalcy with Clay Helton.

In total, they saw four head coaches, including two midseason firings and two interim coaches.

It remains a span that seems unlikely to have been experienced by players elsewhere.

“If they have,” senior linebacker Quinton Powell said, “shout out to them.”

Powell, along with running back Justin Davis, linebacker Michael Hutchings, safety Leon McQuay III, receiver Darreus Rogers and long snapper Zach Smith, came in 2013. After five games that fall, punctuated by a 62-41 loss at Arizona State, USC fired Kiffin in the early-morning hours at an LAX terminal.

Three other seniors, Banner, along with other offensive tackle Chad Wheeler and Jordan Simmons, joined the previous season, as the Trojans became the first preseason AP No. 1 team since 1964 to finish unranked. They went 7-6, losing their final three games, including the Sun Bowl to Georgia Tech.

“This class has been the ultimate battle-tested,” Helton said. “They’ve done a terrific job through the high times and the lows and staying even-keeled.”

A particular challenge for players became the parade of assistant coaches that followed the turnover at the top. Powell and Hutchings played for three linebackers coaches: Mike Ekeler in 2013, Peter Sirmon in 2014 and 2015, and Johnny Nansen this season. It hurt familiarity.

“One minute going with this coach and I have to believe what he’s telling us, then the drop of him, now I got to believe in somebody else. It’s that process of learning who to believe,” Powell said. “I came from Florida and there weren’t too many people that I could’ve talked to because it was, all right, he just left. Now I have to build this relationship with someone who never even recruited me. So it was just the constant, ‘Who do I talk to when I need to talk to someone?’ That kind of what was the hardest thing.”

It helped that Helton brought back Clancy Pendergast as defensive coordinator after he held the same position when they were freshmen.

There was other drama. There was Sarkisian’s alcohol-fueled speech during last year’s Salute to Troy preseason rally. There was Josh Shaw’s suspension for fabricating a story about saving a drowning nephew.

This fall has lately stayed mostly drama-free with Helton remaining at the helm after taking over last October.

Powell’s eyes lit up when asked how it compared to previous seasons.

“Wow, it’s the easiest,” he said.

“Every year was trauma in some type of way. This year has honestly been the first year where we went with the same coaches, same coaching scheme, same everything. It’s kind of just made everything flow. Every year before this one was like, ‘OK, what’s next?’”

It has helped that the Trojans have won seven consecutive games, their longest winning streak since 2008, and can win a second consecutive Pac-12 South division title provided Colorado loses to Utah on Saturday.

Their nearly two-month-long undefeated run has helped ease the sting of the past.

“This season has taken over just about what we’re thinking about, and we’re just having a joy with the second half of this season, what we’re doing as a team, creating something special,” Hutchings said. “I don’t think we’ve really thought about what’s happened the past few years. You’ll probably reflect on that when the season is over, but right now we’re enjoying what we’re doing as a team.”

It’s an easy stretch to enjoy for the seniors, who might finally help the Trojans return to national prominence.

USC, which is ranked No. 12 in both the AP poll and the College Football Playoff rankings, is on the verge of its first Top 10 finish since 2011.

Should it land in the Rose Bowl or win the conference title, those would be feats not seen since the Pete Carroll era.

“Every single one of these guys deserves credit for bringing this team out of the shadows,” Banner said.

To this group, it feels like they are living up to their recruiting promise at last: bringing USC back.

“It’s kind of like I went through the dark days here,” Davis said. “The sunshine is kind of peaking through a little bit. It feels weird to say it in my senior year, but ‘SC, this is why I came here, to achieve this kind of success on the field. It feels good we got all the puzzle pieces right, and I can’t wait for the future.”