Uncertainty clouds USC’s young defensive backfield

After fielding a passing defense that ranked No. 68 in the FBS last year in yards per game allowed, USC has started anew in its secondary — both in terms of personnel on the field and the ones coaching them.

All secondary coaches will enter their first year with the program, including defensive coordinator Clancy Pendergast, who came over from California to replace Monte Kiffin. Graduate assistants Jon Farmerie and Kyle Williams join the team and will assist Pendergast as he juggles his duties as defensive coordinator and defensive backs coach.

On the field, the secondary will also have to deal with the losses of three major players from last year’s roster. Safety T.J. McDonald was selected in the third round (No. 71 overall) of the NFL Draft by the St. Louis Rams, cornerback Nickell Robey signed as an undrafted free agent with the Buffalo Bills and safety Jawanza Starling signed as an undrafted free agent with the Houston Texans.

McDonald, Robey and Starling accounted for a combined 206 tackles (eight for loss) and six interceptions in the 2012 season, with McDonald named to the second-team All-Pac-12.

Though replacing them will be difficult, USC was able to recruit some strong options to shore up the back third of the defense.

Safeties Su’a Cravens and Leon McQuay III, who ranked as the No. 1 and No. 3 safeties in the Class of 2013 by ESPN, respectively, will look to make an immediate impact on the program, along with No. 11 cornerback Chris Hawkins.

“We installed [the defense] over the spring,“ McQuay said. “Starting from the first day of summer, we just started going over it and putting it in slowly again so everybody got it. It’s been going pretty smoothly so far.”

Last year’s returnees in the secondary combined for 111 tackles and three interceptions. Redshirt senior cornerback Torin Harris and redshirt junior safety Josh Shaw return as the secondary’s leaders in tackles with 30 each last season, and Shaw led all returning defensive backs with two interceptions.

Redshirt junior Dion Bailey, who collected 80 tackles and a team-best four interceptions last year, is also moving to safety after playing linebacker the previous two seasons.

None of the starting spots in the defensive backfield are secured, though Shaw, Bailey and senior Demetrius Wright seem to be the frontrunners in the race for the two safety slots after Cravens missed significant time in fall camp due to an undisclosed injury.

“[Shaw] probably knows our defense better than anybody, which is a positive,” Pendergast said. “He gives us flexibility because he’s got cover ability and the ability to play within the box.”

Harris, redshirt junior Anthony Brown and sophomores Devian Shelton and Kevon Seymour are all vying for the two cornerback spots.

“We’re not naming anybody yet, just letting 11 guys line up out there,” Pendergast said. “There’s good competition, and the guys are doing good work.”

Shaw and Bailey aren’t the only two players with versatility in the secondary; Cravens and McQuay can play as nickel cornerbacks, giving Pendergast a variety of looks for opposing offenses to prepare for.

“With some of the guys we have, it will give us flexibility based on the style of offense we’re gonna play [against],” Pendergast said. “We’ve got safeties that have cover ability, so we have some packages where we play three safeties and some where we play three corners.”

The new-look secondary will have a slightly easier schedule to deal with than last season’s, avoiding both Oregon and Washington, which means missing a pair of dangerous dual-threat quarterbacks in Oregon’s Marcus Mariota and Washington’s Keith Price. Last season, those two combined for 502 passing yards, 130 rushing yards and six touchdowns while completing 78.4 percent of their passes against the Trojans.

Though Washington State’s “Air Raid” offense and Oregon State’s two capable quarterbacks in Sean Mannion and Cody Vaz could be problematic for the Trojan defense, neither school’s gunslinger has the running skill of Mariota or Price.

The Trojans, however, still close their season against some strong quarterbacks, such as Stanford’s Kevin Hogan and UCLA’s Brett Hundley, the leading returning passer (3,740 yards) in the conference. And if USC can some how make it to the Pac-12 Championship game, they’ll likely have to face off against Hogan (again) or Mariota, anyway.

But for now, the Trojans aren’t concerned about who they’re playing against; they’re still figuring out who’s going to play for them.

In the past, head coach Lane Kiffin has minimized contact in practices and scrimmages to protect his players, as each healthy body is a precious commodity due to the scholarship restrictions affecting the team’s depth.

But with muddled position battles making it hard to distinguish between the team’s plethora of options in the secondary, the team’s first scrimmage of the fall in the Coliseum was full-contact.

“We’ve had parts of practice live, did the whole [scrimmage] live on purpose so we could evaluate what’s going on,” Kiffin said. “That’s why we wanted to play a bunch of snaps, probably more snaps than we’d normally play at this time of year. Because we want to see them play.”