Defense was the cornerstone of USC’s success during USC’s unprecedented run of seven consecutive Pac-10 titles from 2002-2008.

The defense reached its pinnacle in 2008, when the Trojans allowed just nine points and 221 yards per game, among the best in conference history.

Changes · USC assistant head coach Monte Kiffin has argued allowing tackling in practice would help USC improve defensively in 2011. - Tim Tran | Daily Trojan

But two years later, USC coach Pete Carroll bolted for the Seattle Seahawks and the NCAA placed USC on a four-year probation.  Simultaneously, the Trojans experienced a dramatic dip on the defensive side of the ball.

In spite of such struggles, USC assistant head coach Monte Kiffin, the famed architect of the “Tampa-2” defense, and defensive coordinator Ed Orgeron remain hopeful this spring that the team’s 2010 performance was simply an aberration.

“[The defense] has to be better and it’s going to be,” Orgeron said. “I think they understand the effort and the commitment it takes.”

No doubt the Trojans are in need of an overhaul, after one of the worst seasons in school history — at least statistically, as the 2010 defense surrendered the most yards per game by a USC team since 1955, allowing an astonishly high 400.

Equally disturbing, the team surrendered 26.7 points per game — the second worst mark in school history since the statistic was first calculated.

“We gave up too many big plays, runs or passes,” Kiffin said. “You want to be so good and you start pressing and you try to make too many plays and then you give up the big play.”

The team’s season opener at Hawai’i on Sept. 2 was indicative of things to come, as the Warriors amassed 588 yards of total offense — 459 coming through the air — and scored 36 points in a surprising display of offense.

Later in the year, Washington (536 yards), Stanford (498 yards) and Oregon (599 yards) all torched the young defense.

Part of the reason, at least in Kiffin’s mind, for the defensive difficulties, stemmed from a “no-tackling” policy instituted by his son, USC coach Lane Kiffin, to combat the team’s serious depth issues stemming from the NCAA sanctions that caused players to transfer.

But with the actual season not scheduled to begin for another five months, the policy has been lifted, at least for now.

“The name of the game is tackling the guy with the football,” said the elder Kiffin. “You don’t have to be a scientist to figure that out. We were so banged up last year that we couldn’t [tackle]. And as we practice tackling, we are going to be a better tackling team.”

With the team’s slightly improved play from a year ago in wins over California and UCLA, where the Trojans surrendered just 14 points, and more opportunities in spring practice, Monte Kiffin sees reason for optimism.

“Being the second year in the system the guys understand things a little bit better,” Monte Kiffin said. “They are playing faster. At times last year, we were thinking too much instead of reacting. Defense is really just about getting to the football, making plays and not giving up too many explosion plays.”

But familiarity might be equally as important after 13 games in a new scheme, allowing players the opportunity to adjust. The defense, as a result, appears to have a much better grasp of the concepts this spring.

“[Familiarity] will help us,” Monte Kiffin said. “It’s important just to be back in the system. We lost some guys, but we have some good young players coming in as well.”

Nonetheless, the defense has shown signs of improvement this spring, particularly in its youthful secondary, as three of the four spots at cornerback and safety have already been solidified by junior cornerback Tony Burnett, junior safety T.J. McDonald and sophomore cornerback Nickell Robey.

“It’s pretty good to see three of your secondary positions filled and to feel this good about them this early on,” Lane Kiffin said.

The coaching staff has simplified various schemes in order to showcase the talent on the roster to combat that lack of experience.

“[None of the schemes] are new,” Orgeron said. “We simplified things on defense, so where there shouldn’t be as much thinking and we can play faster. That should help us this year.”