LOS ANGELES — The onslaught began early, and began ruthless, and there would be no mercy on these Trojans on their home turf.

Notre Dame’s offensive line, D’Anton Lynn knew, was good. Probably the best that USC would play all year. But Lynn’s defense looked unprepared from kickoff Saturday afternoon for simply how good.

On the Fighting Irish’s first play from scrimmage, running back Jeremiyah Love took a handoff and plunged unchallenged right up the gut, no Trojan managing to come off a block until Love was already 10 yards downfield.

Then he kept churning, for good measure, and two Notre Dame linemen caught up behind him and simply shoved him an additional 6 or 7 yards through a thicket of Trojans.

The problem, in a 49-35 Notre Dame win Saturday when USC never once led, was not these Trojans’ offensive execution. It was not Lincoln Riley’s play-calling or Jayden Maiava’s two late pick-sixes. The problem was USC has gone three years under coach Lincoln Riley without building fronts at the line of scrimmage — on offense or defense — worthy of the championship expectations he’s professed since he arrived in Southern California.

It was a problem after a sterling 2022 season crumpled late when Riley professed “our guys don’t look like that” in comparison to Georgia’s defensive line. It was a problem after a shaky 2023 season crumpled late when Riley admitted Oregon simply outplayed USC at the line of scrimmage in a November loss.

It was a problem on Saturday at the Coliseum, the final gut-wrench in an indefensible 6-6 season as Notre Dame ran over USC to the tune of 258 yards and often sent running backs free through open holes without any contact.

“Kind of the story of the day was — we didn’t defend the run as well as we have been,” Riley said. “And I thought that made them pretty multi-dimensional.”

Beyond simple execution, though, this seemed destined to happen, from a sheer talent deficiency on both fronts. Offensive line coach Josh Henson had done an admirable job of rounding USC’s offensive line into form after much-documented early season struggles. Lynn has generated some pressure recently with creative blitz packages and freshman depth.

But both sides were overwhelmed Saturday afternoon. USC’s blockers surrendered 15 pressures and their defense was credited with just eight while Notre Dame surrendered just four and generated 26, according to Pro Football Focus.

Look deeper, and it was perhaps the most stark example of a season-long trend. In a 6-6 season, USC’s opponents cumulatively generated more pressures (183 to 166) and surrendered fewer (109 to 122) than the Trojans, according to data compiled from PFF.

There are a few reasons for optimism, across USC’s roster and recruiting efforts, that signal times could change in 2025. If the Trojans’ current recruiting class holds, they’ll import a couple of four-star offensive tackles in Utah’s Aaron Dunn and Georgia’s Alex Payne. Left tackle Elijah Paige, at 6-foot-7, has responded admirably after a rough early and midseason run, allowing just seven pressures total in his last five starts.

“I think there’s a lot of guys that are going to be big-time players for us, and depth,” Riley said of USC’s young offensive linemen, “and has a chance to be championship-quality depth here pretty soon.”

Riley, too, has been adamant that continuing to develop and acquire pass-rush talent is a “big part of looking forward” for USC’s program, as he said in October.

USC is making a highly public push for 2025 edge Jahkeem Stewart, needing to secure defensive line depth before Wednesday’s early signing day. Freshmen Kam Fountain and Sam Greene, meanwhile, straight-up beat out more senior talent for USC’s starting edge spots in the last stretch of the season, both showing promise as pass rushers and intellect in containing dual-threat quarterbacks.

“The more we give them,” Riley said a couple of weeks ago after USC’s win over Nebraska, “the better they get.”

There is growth, certainly. But until USC’s fronts look more like the Notre Dame freight train that steamrollered on Saturday, they’ll be hard-pressed to achieve Riley’s visions of glory in Southern California.