Rookie Kendall Hunter continues to make a case that he, and not second-year player Anthony Dixon, should be Frank Gore's primary back up this season. Hunter entered the game as the NFL's leading rusher in the exhibition season and immediately started to pad his lead. Hunter carried the ball six times for 46 yards on the opening drive, including a 21-yard scamper on third and short.
Frank Gore started the game at tailback but left before getting a carry. While Dixon had gotten into the game ahead of Hunter in the three previous preseason games, Hunter took the first carry for the 49ers Thursday.
Dixon only carried the ball once on the opening drive but it was for a one-yard touchdown. Dixon scored again from one yard out at the end of the first quarter. That drive was set up when linebacker NaVorro Bowman sacked Chargers starting quarterback Billy Volek, forced a fumble and then recovered it at the San Diego 22.
As is typically the case in the fourth preseason game, San Diego did not play many of its top starters, including quarterback Philip Rivers, tight end Antonio Gates, receivers Vincent Jackson and Malcom Floyd and outside linebackers Larry English and Shaun Phillips. Bowman is playing next to Patrick Willis this season after Willis' long-time linebacker mate, Takeo Spikes, signed a free-agent contract this year with San Diego. Spikes started the game for the Chargers as did another former 49er, Travis LaBoy.
Jim Harbaugh and the 49ers continued to tinker with their lineups. Jonathan Goodwin started the game at center and was in on the team's first two scoring drives. The 49ers' offensive line, which had rough outings in the first and third preseason games, rebounded against the Chargers.
Left tackle Joe Staley, who struggled in Saturday's loss to the Texans, opened a wide hole for Hunter on his 21-yard scamper. Both of Dixon's touchdowns came when he burrowed in behind the right side of the line, in particular guard Chilo Rachal.
Quarterback Alex Smith was an efficient 7 of 9 for 42 yards before giving way to Colin Kaepernick at the start of the second quarter.
Kaepernick displayed the same elusiveness that vexed opponents when he was at Nevada, buying time with his feet and weaving through the defense for first downs. But he also showed why the 49ers may not be able to rely on him, at least early in the season.
The rookie has been accurate downfield when he puts everything he has into his throws. But he is still getting the feel of touch passes at the NFL level. One of them, a fade attempt to receiver Lance Long in the second quarter was underthrown and intercepted. Another attempt, this one a bullet to rookie Ronald Johnson on a slant, was tipped up and intercepted. Kaepernick threw five interceptions in the preseason.
While Kaepernick was going through the typical growing pains of a rookie quarterback, fellow draft pick Aldon Smith was causing headaches for the San Diego offensive line.
He recorded two sacks after replacing Parys Haralson in the first half and was close on two others.
-- Matt Barrows