NEXT GAMEWHO: No. 7 South Carolina (3-0, 1-0 SEC) vs. Missouri (2-1, 0-1 SEC)WHEN: Saturday, 3:30 p.m. WHERE: ColumbiaTV: WSCS (CBS) LINE: South Carolina by 10

COLUMBIA — Much of the optimism surrounding South Carolina’s offense entering this season stemmed from Marcus Lattimore returning from a knee injury to join quarterback Connor Shaw in the backfield. Lattimore had long since proven himself as one of the nation’s best backs, and Shaw developed into a capable passer late last season.

Replacing receiver Alshon Jeffery was going to be a significant task, but between Lattimore, Shaw and a sizable pool of receivers, the Gamecocks seemed to have enough skill players back to improve on last season’s 373.5 yards per game, which ranked No. 73 nationally.

It might have been easy for the casual observer to overlook the absence on this year’s preseason depth chart of Rokevious Watkins and Terrence Campbell. Watkins began last season, his second as a starter, as the right tackle, then moved to the left side. Campbell, also a second-year starter, anchored the right guard spot. The Gamecocks also lost left tackle Kyle Nunn, who started five games in 2011, increasing his career total to 21.

Despite losing three experienced linemen, the Gamecocks seemed to benefit, in at least one way, from Nunn’s inability to stay healthy last fall. True freshman Mike Matulis and redshirt freshman Cody Gibson were both able to start at right tackle during the final eight games.

So USC had just two truly new starting linemen for 2012 — redshirt freshman left tackle Brandon Shell and junior right guard Ronald Patrick. Yes, left guard A.J. Cann is still just a sophomore, but he started all of last season. And the center, who must be the line’s mentally sharpest player, is senior T.J. Johnson, a third-year starter.

Yet while USC’s offense has been productive through three games, largely by gashing two overmatched defenses, the line has left its position coach, Shawn Elliott, frustrated and hoping for a better performance in Saturday’s 3:30 p.m. home game against Missouri.

The Gamecocks are undefeated and averaging 433.7 yards, including 528 and 501 the past two weeks against East Carolina and Alabama-Birmingham to goose the average. But they also have allowed nine sacks, tied for most in the Southeastern Conference, despite attempting 27.3 passes per game, ninth in the league. Last season, they allowed 30 sacks in 13 games.

USC allowed three sacks against UAB, and Elliott said his line played well for parts of that game, but not nearly well enough for most of it. Coach Steve Spurrier said earlier this week that the line’s shortcomings in the UAB game, particularly in run blocking, could result in at least one new starter for the Missouri game. Elliott did not back away from that assertion Wednesday.

“Well, I can tell you about the changes we’re going to make,” Elliott said. “Hopefully, we’re going to get out there and block somebody’s tail off Saturday night instead of lying around on the football field like we did last week. I would anticipate some changes (in the starting lineup). I’m just not real sure at this point if I want to bring that out in the open.”

Because Shell was demoted to backup right tackle after the season opener at Vanderbilt, the starters for the past two games have been Matulis, Cann, Johnson, Patrick and Gibson.

Change could come at tackle, as Spurrier volunteered that Shell, a Goose Creek High graduate, “played pretty decent” against UAB, and said, “We have to get Brandon Shell back on the field a little bit more.” No. 2 center Kyle Harris, a redshirt freshman, practiced at center and guard this week, as Elliott searches for answers he is intent on finding.

He said the struggles against UAB had more to do with botching assignments than poor effort, but he did not expect so many “mental busts,” especially since they didn’t happen in the first two games.

“I was just really disappointed,” he said. “There were times that those guys went in there and did well. But all in all, it was such a, I thought, just a pitiful effort. It was an embarrassment as a coach. It was an embarrassment to our players. Certainly, I can tell you one thing: If change isn’t made, it probably needs to be made with me, because that was a horrible performance.

“You can only spoon-feed these guys so much. We have run the same plays over and over and over. And there are only so many (defensive) fronts in football that you’re going to see. So nothing should surprise them.”