Rapid Reaction: 49ers 34, Packers 28

SAN FRANCISCO -- Rapid reaction from the Packers’ 34-28 loss to the San Francisco 49ers on Sunday at Candlestick Park:

What it means: The read-option offense didn’t beat the Green Bay Packers. Anquan Boldin did. In his first game with the 49ers, the former Baltimore Ravens receiver exposed another problem with the Packers’ defense. 49ers quarterback Colin Kaepernick’s new favorite target caught 13 passes for 208 yards and a touchdown. Kaepernick threw for 412 yards and three touchdowns.

Stock Watch: Considering the 49ers ranked fourth last season in rushing defense, it may not be fair to judge whether the Packers’ running game has improved. But the numbers weren’t pretty. They rushed for just 63 yards on 19 attempts. Combine that with the fact that starting running back Eddie Lacy, in his first NFL start, lost a fumble in the second quarter. Lacy finally got going in the fourth quarter. Lacy capped a go-ahead drive that gave the Packers a 28-24 lead with 8:20 remaining with a 2-yard touchdown leap over the pile. He carried five times for 26 yards on the drive. The problem was Lacy carried nine other times for just 15 yards.

Trouble up the middle: Without safety Morgan Burnett and slot cornerback Casey Hayward, both sidelined with hamstring injuries, the Packers had all kinds of trouble defending the middle of the field. The safeties were responsible for the 49ers’ first two touchdowns, a 20-yard pass from Kaepernick to tight end Vernon Davis against M.D. Jennings in the first quarter and a 10-yard pass from Kaepernick to Boldin in the second quarter.

Sitton struggles: Josh Sitton, in his first game since moving from right guard to left guard, struggled. He was penalized three times -- once for illegal hands to the face and twice for holding -- and didn’t fare well in the running game.

Up-and-down debut: Rookie left tackle David Bakhtiari drew a tough assignment in his first start, facing Aldon Smith, who finished second in the NFL last season with 19.5 sacks. Bakhtiari gave up two sacks to Smith but those may have been his only two bad plays.

What’s next: The home opener is Sunday against the Washington Redskins, who will be coming off a short week after playing the Philadelphia Eagles on Monday night.