LOS ANGELES -- The Southern California defense was historically bad last season, and its attempt to bounce back got tougher when an assistant coach resigned two days before the Trojans' opener.
USC defensive secondary coach Willie Mack Garza stepped down Thursday, citing personal reasons in a terse news release.
"I have some personal issues unrelated to USC that I need to address," said Garza, a former defensive back at Texas. "I wish the Trojans the best, and I am sorry I won't be with them in what I know will be a very successful season."
USC declined to comment on reports claiming Garza's abrupt departure was linked to the school's discovery that Garza once had a relationship with Willie Lyles, the scouting service owner and street agent tied to an NCAA probe at Oregon and LSU.
USC is playing under heavy NCAA sanctions, including a bowl ban, severe scholarship restrictions and four years of probation. The school's beefed-up compliance department has dealt aggressively with even tangential connections to impropriety under new athletic director Pat Haden, who didn't immediately comment on Garza's departure.
The Trojans announced Garza's resignation after Thursday's morning practice, which Garza didn't attend. USC's players found out about the resignation through a text message from coach Lane Kiffin.
Safety T.J. McDonald, the Trojans' top returning tackler, tweeted: "Wow," and "For those worried, we are going to be just fine!"
Garza joined the USC staff in January 2010, leaving Tennessee along with Kiffin, assistant head coach Monte Kiffin and defensive coordinator Ed Orgeron. He's just one contributor to the Trojans' defensive game plan, working mostly with USC's cornerbacks, but the school can hardly afford any distractions or depletions while attempting to rebuild last year's unimpressive unit.
Starting with Saturday's opener against Minnesota at the Coliseum, the Trojans are cautiously confident they'll be better this season.
"Yeah, because I don't think it would get much worse," McDonald said earlier this week.
Even with Monte Kiffin's celebrated Tampa 2 defense and Orgeron's bulldog motivational skills, USC's defense yielded 400 yards per game -- the most since the school started keeping records in 1955 -- and three 500-yard games. The Trojans gave up a school-record 347 points, including six games with at least 30 points allowed.
The decline was stark after several years of dominant defenses under former coach Pete Carroll, particularly in a defensive secondary that often seemed confused or overmatched. USC managed just 15 interceptions while giving up 259.5 yards passing per game, USC's most since 2003.
"I know there was a lot of things that went wrong with our defense last year, but we're fixing them," defensive end Nick Perry said. "We've got players that can dominate this game, and we're learning how to go out there and do it."
The Trojans have changed their approach in Monte Kiffin's second season. USC installed its defense more deliberately, making sure the players understood each step along the way, and the Trojans have done more tackling in practice after Lane Kiffin avoided contact drills last summer, trying to keep his sanctions-depleted roster mostly healthy for the regular season.
"We feel better, but I felt pretty good going into last year," Lane Kiffin said. "The truth will be in how we tackle and play. We'll find out Saturday."