SAN DIEGO – Through three weeks of preseason games, the San Diego Chargers have the worst run defense in the league, giving up 5.58 rushing yards per play.

Yes, preseason games are not always a good measure of what will happen during the regular season, but San Diego’s inability stop the run continues a disturbing trend from last season, when the Chargers allowed 4.6 rushing yards per play, No. 27 in the league.

The Chargers allowed 243 rushing yards and four rushing touchdowns by quarterbacks in a 41-14 loss at Seattle last week.

The Chargers haven’t been much better defending the pass. Through two preseason games, opposing quarterbacks have posted a 92.3 passer rating. The Chargers have just four sacks in two games.

Those humbling numbers have San Diego players looking for a rebound performance against a pretty good offense when they face the San Francisco 49ers on the road Sunday.

“We’re still trying to find our identity for 2014, and make sure we don’t stink this season up,” Chargers defensive tackle Corey Liuget said. “We want to make sure that we come out and play well, and do what we love to do, which is play football and play defense.”

Added middle linebacker Donald Butler: “I’m ready to get back on the field after that debacle that we showed on Friday. It will be good to get back out there for some live reps.”

Chargers defensive coordinator John Pagano boiled down his team’s issues on defense to two things that need improvement: tackling and pressuring the quarterback.

“Those are two things that we didn’t do a great job of last year,” Pagano said. “I thought we did better late in the year, and that really changed for us. Getting the guys back healthy late in the year was big, but it’s just going out and making sure that we're fundamentally sound and playing with incredible effort.

“But those two things are things that we need to do better as a defense.”

Injury update: defensive end Lawrence Guy (shoulder), linebacker Manti Te'o (foot), defensive end Sean Lissemore (ankle), receiver Vincent Brown (calf), cornerback Marcus Cromartie (unknown) and safety Jahleel Addae (hamstring) did not practice on Thursday. Running back Kerwynn Williams (unknown) returned to practice after missing Monday and Tuesday’s workouts. Offensive lineman Jeromey Clary (shoulder/hip) remains on the physically unable to perform list. ... Chargers kicker Nick Novak turned 33 years old on Thursday.