San Diego, CA (SportsNetwork.com) - The Dallas Cowboys' biggest weakness heading into the 2014 NFL season is on the defensive side of the ball.
That area was a problem in 2013, and it remained a problem in the Cowboys' 27-7 preseason loss to the San Diego Chargers on Thursday.
Dallas lost DeMarcus Ware and Jason Hatcher to free agency and then saw middle linebacker Sean Lee suffer a season-ending knee injury. Rod Marinelli, the Cowboys' first-year defensive coordinator, is in charge of trying to improve that side of the ball.
The Chargers, who went 9-7 last season before losing to the Denver Broncos in the Divisional Round of the playoffs, racked up 395 yards of total offense on Thursday.
San Diego lost offensive coordinator Ken Whisenhunt, who moved on to become the head coach of Tennessee. Frank Reich was promoted from QB coach to offensive coordinator.
Philip Rivers played one series and completed all four of his passes for 61 yards. Kellen Clemens connected on all five of his passes for 134 yards and a touchdown. Brad Sorensen completed 5-of-7 passes for 48 yards.
Rookie running back Branden Oliver carried the ball seven times for 64 yards and a score San Diego, which had 152 yards on the ground. Dontrelle Inman caught three passes for 107 yards and a touchdown.
With Tony Romo sitting out to rest his surgically repaired back, Brandon Weeden got the start for the Cowboys. The former Browns quarterback completed 13-of-17 passes for 107 yards and a touchdown.
Tight end Jason Witten and running backs DeMarco Murray and Lance Dunbar also sat out for Dallas, which has finished 8-8 the past three seasons.
Joseph Randle carried the ball 13 times for 50 yards in the loss.
Running back Ryan Mathews fumbled on San Diego's first possession of the game. Dallas recovered and Weeden led the Cowboys on an 11-play, 80-yard scoring drive. Weeden rolled to his right and completed a 4-yard TD pass to tight end James Hanna in the back of the end zone.
San Diego responded with a touchdown of its own. Oliver capped the 80-yard march with a 16-yard touchdown run.
With less than two minutes to play in the half, Nick Novak made a 24-yard field goal to make it 10-7 Chargers.
Clemens hooked up with Inman for a 70-yard score on San Diego's second possession of the third quarter. After Caleb Hanie fumbled, Kerwynn Williams scored from one yard out to make it 24-7.
Novak made a 44-yard field goal early in the fourth.
08/08 01:25:11 ET