As the Trojans move into the fourth week of spring ball drills, the coaches are still searching to balance the desire for physical play with the need to keep players healthy on a reduced roster.

When Steve Sarkisian set the agenda for spring ball, he made it clear that one of his goals was to have all the injured players healthy for the fall. With injured veterans like Leonard Williams and Josh Shaw, the decision was made to sit them out entirely. And there was a lot of caution shown in terms of bringing other players back as well.

Sarkisian chose to focus a lot of attention this spring on the installation of new schemes on both sides of the ball, including morning walk-throughs and in-practice teaching sessions that would allow those injured players the opportunity to mentally stay with the rest of the team.

One of the trade-offs has been fewer opportunities for live tackling during practice, a concession that no coach wants to make but that sometimes can come into play. There were a few dozen live plays during a recent practice session at the Coliseum -- including a spirited Oklahoma drill -- and other isolated physical sessions, but they have been limited in scope.

“You would love to practice [live tackling] all the time, but you have to be smart about the way you do it,” USC defensive coordinator Justin Wilcox said. “You work on tackling in controlled environments where you limit the number of bodies potentially going to the ground, you work that way in one-on-one drills, you work it on bags. But when you get to go live, you have to go. There’s nothing like live tackling.”

It’s not like the Trojans don’t have plenty of opportunities to tackle if they want. Through nine days of spring ball, the new up-tempo offensive system has run more than 1,000 plays (more than 2,000 if you include morning walk-throughs), and there is an added benefit there as the defensive players must also adapt quickly to the new pace of play.

“The offense can have the advantage late in the game with the up-tempo,” Sarkisian said. “That’s why we practice this way, to prepare for games.”

That late-game advantage would be evident based on what Wilcox has seen so far from his defense.

“We have a tendency to start practices fast and we play well for the first half, but we don’t do as well in the second half,” Wilcox said. “That’s where we have to continue to emphasize finishing strong because the end of the game is when you get up there in play count. When you get to plays 100 to 120, that’s when you really need to sustain things mentally and that’s something we’ve got to work on. The effort has been good, we just have to get better. I would have thought through nine days that we would have it down pat and look great, but I don’t know if that’s reality.”

It would be natural to expect things to look better in the fall, especially when so many of the injured players return. In addition to starters such as Williams and Shaw, there are also players with starting experience like J.R. Tavai, Lamar Dawson and Anthony Brown who are expected back in action.

In the meantime, other players will continue to fill in during the last two weeks of spring to get as much experience as they can.

“With the injured guys out, there’s some guys taking reps right now who won’t be getting reps in the fall,” Wilcox said. “But that’s OK, we need everybody and you’re always looking to build on your depth. It’s a chance for those guys to show us something to maybe earn a bigger role.”