SAN DIEGO -- A weekly look at what the San Diego Chargers must fix:

When the San Diego Chargers host winless Jacksonville for a Week 4 contest at Qualcomm Stadium, one of the issues San Diego offensive coordinator Frank Reich will attempt to resolve is jump-starting the run game.

The Chargers are averaging a league-worst 2.43 yards per carry. One of the concerns for San Diego is depth. The team’s top two running backs, Ryan Mathews and Danny Woodhead, are not available due to injuries. Donald Brown finished with 31 carries for just 62 yards in a win against Buffalo over the weekend.

In the second half against the Bills, Brown ran the ball 15 times for 7 yards, with seven of those carries going for either 0 or negative yards.

Brown is new to the offense, so establishing cohesion with the offensive line and getting the right read as to where the running lane is going to open up could be an issue. However, Chargers coach Mike McCoy was not buying that as an excuse.

“Donald has played plenty of football,” McCoy said. “To me, inside zone is inside zone, it doesn’t matter where you’re running it. Outside zone is outside zone. Power is power. We just have to do a better job of executing it.”

San Diego also could change up the bread-and-butter plays it uses in the running game, adding more misdirection plays like traps or counters in an attempt to create better blocking angles for the offensive line at the point of attack.

Finally, the Chargers could consider using fullback/tight end David Johnson more. Having a lead blocker at the point of attack could help clear up the trash, giving Brown and the rest of San Diego’s runners a better chance to get positive yards before getting hit at the line of scrimmage. Johnson has played an average of 16 plays in the first three games.