ST. LOUIS -- It's a weekly topic at Rams Park: What's wrong with a defense that can't stop the run?

The St. Louis Rams had an excuse when they were getting gouged by LaDainian Tomlinson and Larry Johnson, because those running backs put up big numbers against a lot of teams.

Still, it's quite another story when Panthers backup DeAngelo Williams gets 114 yards in last week's 15-0 victory. Or Seahawks backup Maurice Morris racks up 124 yards with a 5.9-yard average.

Despite a concentrated effort to improve the defense in the offseason, the Rams are next-to-last in the NFL against the run. The Panthers totaled 242 yards last week, St. Louis has surrendered seven 100-yard games, and the opposition is averaging 153 yards on the ground.

Every time out, it's been the same, frustrating scene.

"I see the same thing every week, I see the same thing on film every week -- a guy out of his gap, a guy trying to overcompensate for someone, a guy trying to make a play when it's not his," defensive end Leonard Little said.

"We're making a lot of mental mistakes, and that's the biggest thing about us now. Guys have just got to take it upon themselves to be where they want to be every play."

The Panthers had so much success against the Rams that they were able to play an effective game of keep-away, running the ball 43 times and dominating in time of possession at nearly 39 minutes. Big plays helped the Rams minimize the damage, but not enough given a truly awful day by an offense that mustered only 111 yards.

The Rams added tackle La'Roi Glover, safety Corey Chavous, middle linebacker Will Witherspoon and cornerback Fakhir Brown in the offseason, plus drafted cornerback Tye Hill in the first round. Defensive coordinator Jim Haslett is the former head coach of the Saints.

In practice, they've put an emphasis on stopping the run for several weeks now.

"It's not like we're not working on it," head coach Scott Linehan said. "We're adding plays to our practices in our run periods and we're still looking for the answer."

Yet the struggles continue. The Panthers had seven carries of 10 yards or longer, including a 17-yarder by fullback Brad Hoover from the Carolina 1 in the first quarter. That was one of three long gainers on the same drive.

Little is a standout at one end, but the rest of the line has been outplayed. Jimmy Kennedy is in his first year at nose guard and he's learning on the job. Rookie end Victor Adeyanju was thrust into a starting role when Anthony Hargrove, who skipped two games of practices and meetings earlier in the season, was traded to Buffalo.

Behind them, Will Witherspoon is in his first year at middle linebacker. Outside linebacker Pisa Tinoisamoa is basically a one-armed player due to a dislocated left elbow and broken left hand. So he has an excuse for missing some stops.

"I've found myself trying to funnel the ball back to other people, where I could just make the tackle on my own," Tinoisamoa said.

He may be on to something. This week, the Rams are emphasizing gang-tackling.

"The play-calling is good and we're in position, but it's just that one break and that's all it takes," he said. "We just need to get more guys to the ball.

"Our goal this week is not to have it on that one guy."