RENTON — The Seahawks hope to beat the 49ers this weekend by running the ball down their throats.

In reality, however, beating San Francisco will likely require a strong performance from quarterback Tarvaris Jackson. The 49ers lead the league in run defense both in terms of yards allowed per game and per carry. To move the ball, the Seahawks will either have to do something almost no other team has done this season, or turn to Jackson to provide an offense spark.

The good news for the Seahawks is that calling on Jackson to make plays may not be such a bad idea. Not the way he has played of late. While the running game and defense have, rightly so, gotten a lot of the credit for Seattle’s second-half turnaround, Jackson has been playing very well over the past few weeks. Since throwing two interceptions to start the game in St. Louis last month, Jackson has thrown just one interception compared to six touchdowns in his past 131 attempts, and has gone his past three games without a pick. He has a passer rating of 90 or better in three straight games, something that hasn’t been done by a Seahawks quarterback since Matt Hasselbeck finished the 2005 season on a very impressive roll.

In last weekend’s win over the Bears, it was Jackson’s play, not the running game, that sparked the offense in the second half. After struggling in the first half, he completed 15 of 19 passes in the second half for 176 yards and a score.

The most obvious reason for Jackson’s improved play is his improved health. He missed only one game and part of another after injuring a pectoral muscle against the New York Giants, but after returning to action it was clear Jackson was playing through pain. Not only did the injury affect his ability to make some throws, but it also caused him to be extremely limited in practice. Jackson is healthy now and has been practicing fully for the past three weeks, which, not coincidentally, have coincided with a run of strong play.

“He’s on a real good run right now, I think, since he got healthy,” Seahawks coach Pete Carroll said. “He’s going to improve through the last few games of the year here. He’s going to keep getting better because he’s physically OK. He was not that way.”

Jackson’s improvement likely isn’t only health related, however. Some of it just has to do with him gaining more experience and building chemistry with new teammates. As long as Jackson has been in the league, it’s easy to forget he’s still relatively inexperienced as a starting quarterback. Prior to this season, he had started just 20 games during a five-year career in Minnesota, hardly a large body of work at the game’s hardest position.

“He’s been in the league a long time but he hasn’t had all the starts, and I think that’s what’s been great for him,” said offensive coordinator Darrell Bevell, who also coached Jackson in Minnesota. “I remember a time in Minnesota when he was in and out, in and out, in and out, so there was never the consistent string of starts back to back. He’s been able to do that this year and get that opportunity and so he’s seeing things over and over and I think he’s improved each week he’s stepped out there.”

All season long, Jackson has talked about how much it meant to him to come to a situation where he was wanted and where he knew he had the starting job. Over the past few weeks, he has rewarded the Seahawks for their confidence in him.

“It helped me a lot,” he said. “I was able to get comfortable. I was able to settle in a little bit and play week-in and week-out instead of having to come in and play a couple games and then sit and stuff like that. So I’m just able to get confident, get everybody on the same page.”

Jackson hasn’t done enough to convince most people that he should be the quarterback in Seattle for years to come, but he has also played well enough that the Seahawks won’t need to panic come draft time an take a quarterback in the first round no matter who is available. Whether or not you believe the Seahawks can win a Super Bowl with Jackson, we have seen that they can win with him.

Seattle is 7-5 in games Jackson has started and 7-6 in games he’s played, and as the offensive line and running game have come together, the Seahawks are 5-1 in second half of the season. Now does that mean they’re winning strictly because of Jackson? Not at all, but if the question is, can they win with him, well then, yeah, they already are. And really, that’s what Carroll is looking for. He wants a team that plays good enough defense and runs the ball well enough that the quarterback isn’t asked to do everything. If this team functions well enough in those areas, it can succeed with Jackson.

“We don’t want the quarterback to be the guy that has to carry the whole load,” Carroll said.

On Saturday, however, against an incredibly stingy run defense, expect Jackson to carry a little more of the load that usual.

Herald Writer John Boyle: jboyle@heraldnet.com. For more Seahawks coverage, check out the Seahawks blog at heraldnet.com/seahawksblog