SAN FRANCISCO — The Seahawks offense was only half bad on Sunday.

And that first half was absolutely horrible, with the Seahawks managing just 37 yards. But the half that followed offered at least a glint of hope after Seattle's 33-17 loss at Candlestick Park.

"We made progress," coach Pete Carroll said. "And we'll build from there."

Progress is something that was hard to see before halftime. The only time Seattle crossed midfield was on its opening drive. And quarterback Tarvaris Jackson was subject to an abject beating as he was sacked three times.

"It's just unacceptable to do what we did in the first half and expect to win games," center Max Unger said.

Robert Gallery was out because of a sprained knee, which left rookie James Carpenter the starter at left guard and made Unger and his 17 regular-season starts the most experienced starter on the offensive line. Left tackle Russell Okung had 10 starts entering the game. The other three starters — Carpenter, rookie John Moffitt and Breno Giacomini — were starting their first games.

It was the least experienced starting offensive line for an NFL team since 1995. The Carolina Panthers started five linemen with a combined 27 regular-season starts in Week 2 that season — the second game in franchise history.

Of the three first-half sacks, the one that hurt the most came from linebacker Parys Haralson, who clobbered Jackson into a fumble that gave San Francisco the ball at the Seattle 9. The Seahawks defense held the 49ers to a field goal.

"It was frustrating," Jackson said. "The defense was playing their butt off. We put them in some bad situations."

The Seahawks gained 56 yards on their first drive of the second half — 19 more than they totaled in the first half — and finished the drive with an 8-yard touchdown pass to Golden Tate.

The Seahawks reached the red zone three times in the second half after not crossing the 40 in the first half.

Jackson suddenly had time to pass and he guided the offense. What changed up front?

"I think that they felt more comfortable," Carroll said. "They settled down and they saw things more clearly. They communicated better, and everything just picked up."

Was it possible to see progress in the way Seattle's young line came together in the second half?

"There's no question about that," Unger said. "We moved the ball, got ourselves in a position to come back in the game, couple of good drives. But like I said, there's no way we can expect to win against a good team like the 49ers when you have a first half like that."

Danny O'Neil: 206-464-2364 or doneil@seattletimes.com