Defensive problems are something Trojans need to tackle right away

USC spent much of Friday relaxing in Hawaii, deviating from its usual trip itinerary of flying home immediately after games.

But the Trojans’ performance in a 49-36 season-opening victory over Hawaii the night before left at least one coach feeling antsy.

“We have to go back to work as soon as we can,” said Monte Kiffin, USC’s assistant head coach for defense.

Kiffin’s unit gave up 588 yards to Hawaii’s offense, but the veteran coach wasn’t overly stressed. More than four decades of coaching and overseeing college and NFL defenses has taught him that first-game performances are not necessarily indicative of how teams might develop.

“I’ve said all along we’re young and we have some guys that have not played a lot,” he said. “But they’re going to be good.”

Still, it’s tough to believe that Pacific 10 Conference coaches such as Oregon’s Chip Kelly, Washington’s Steve Sarkisian, Stanford’s Jim Harbaugh and Oregon State’s Mike Riley will look at the Hawaii tape and not see opportunity.

USC failed to produce a consistently strong pass rush, committed numerous penalties that kept drives alive, and missed a substantial number of tackles. The secondary was spinning and middle linebacker Devon Kennard, making his first start, was exploited several times in deep coverage.

Hawaii didn’t just pick on the young starters such as freshman cornerback Nickell Robey and sophomore safeties Jawanza Starling and T.J. McDonald. On the first play from scrimmage, quarterback Bryant Moniz went after senior cornerback Shareece Wright.

Even after linebacker Michael Morgan knocked Moniz out of the game with a third-quarter tackle, third-stringer Shane Austin dissected the secondary and passed for two touchdowns. The Warriors’ 36 points were the most surrendered by the Trojans in an opener since 1976, when Missouri beat USC, 46-25, at the Coliseum in John Robinson’s first game as coach.

Wright said the aerial onslaught was “good” for the Trojans.

“It’s a test that we needed and now we see where we’re at and now we can see what we can get better at,” he said.

After the game, Coach Lane Kiffin said Hawaii had switched from its typical run-and-shoot formation to the so-called “pistol,” in which a running back lines up directly behind the quarterback rather than to the side. USC coaches identified the change by watching a local news broadcast Wednesday night.

“Our defense spent all morning preparing for it and I guess we wished we hadn’t watched the news . . . because it didn’t help very much,” Kiffin said.

Monte Kiffin, the head coach’s father, said the switch was not the problem.

“The routes were basically the same,” he said. “That really wasn’t a factor.”

Poor tackling was, though.

The Trojans refrained from tackling for all but one day of training camp because coaches did not want to risk depleting a roster already thin at several key positions. Lane Kiffin acknowledged that he was concerned about how the moratorium would affect his team.

Hawaii exploited the situation by substituting liberally and by rushing the ball with Moniz, and with running backs Alex Green and Chizzy Dimude in the second half. Dimude averaged more than 10 yards a carry.

“We were running them because we knew [USC] couldn’t tackle them because they were gassed,” Hawaii Coach Greg McMackin said.

However, USC coaches repeatedly pointed to lack of discipline as the main reason for breakdowns.

“We really messed up on some simple things,” defensive coordinator Ed Orgeron said, adding, “It’s all things that we can fix.”

USC has a week to do so. The Trojans play Virginia next Saturday at the Coliseum.

gary.klein@latimes.com