SANTA CLARA, Calif. — J.T. O'Sullivan knows he's in for a beating this year, and he doesn't mind.

To be at the controls of San Francisco offensive coordinator Mike Martz's high-risk, high-reward schemes, the veteran coach's quarterbacks over the last seven seasons had to absorb more than their share of sacks. Through four games of Martz's first season with the 49ers, O'Sullivan has been dropped a league-leading 19 times.

Although Martz doesn't want his passers to get pulverized, it seems inevitable because of the offense's long receiving routes and patient plays, which give pass-rushers more time to reach their target.

O'Sullivan knew these beatings were coming after he was sacked three times in just one appearance in Martz's offense last year with the Detroit Lions. He's more than willing to absorb a little punishment if it pays off in points and wins for a club that had precious few of either last season.

"I'm looking to hang in there as long as I can and make the throws down the field," O'Sullivan said Wednesday.

The 49ers (2-2) have yielded six more sacks than any other NFL team except Pittsburgh and even four more than last year at this point, when the porous Niners lost quarterback Alex Smith to a season-ruining shoulder injury in Week 4.

In his first season as a starter, O'Sullivan has impressive stats and is perfectly healthy, but has committed four fumbles and thrown three interceptions while enduring criticism for holding the ball too long in the pocket. The offensive line has been criticized for the sacks, and the linemen have accepted the blame — but recent history shows no line can keep a Martz quarterback off his back for long.

"In this offense, sometimes the quarterback has to hold it to get the ball downfield for those big chunks (of yardage) that you see," left tackle Joe Staley said. "J.T. is just trying to make a play. We've just got to do a good job of keeping that pocket tight up front and then running the end guys around the edges."

No matter how much the players and coaches insist the Martz offense gets a bad rap for quarterback abuse, Martz's past six teams have all been sacked more frequently than their opponents.

In 2002, St. Louis' Kurt Warner was sacked 21 times and missed nine games with injuries to his finger and hand. The Rams were sacked 43 times in 2003 and 50 more in 2005, when Marc Bulger missed most of three games with a shoulder injury after a sack by the 49ers' Bryant Young.

But Martz's two offenses in Detroit reached new frontiers in quarterback punishment. With a sub-par offensive line and plenty of early deficits that required a pass-heavy game plan, the Lions were sacked 117 times in the last two seasons, including 63 in 2006 and a league-leading 54 last season.

But Jon Kitna, Warner and Bulger all missed remarkably little playing time considering the punishment they took, so perhaps injury is less of a concern than the field position eaten up by repeated sacks — and that's where Martz's boosters claim his offense makes up for the losses with big gains.

"That's one thing about Mike's offense, they've always been able to overcome that," said Patriots coach Bill Belichick, who will face the 49ers on Sunday at Candlestick Park. "They've been able to overcome a second-and-20 or a third-and-15 because of their efficiency in throwing the ball down the field. Third-and-10 is no big deal to them.

"It's a lot to defend, and yeah, the defense makes a couple of plays here and there, but they are making a lot of plays on offense to offset it. That's the trade-off."

Indeed, San Francisco is third in the league in pass plays totaling 20 yards or more, behind only Dallas and Denver. That's a refreshing achievement for a club that had the NFL's worst offense in two of the past three seasons, and the 49ers will eagerly take the trade-off.

Coach Mike Nolan claims San Francisco has plenty of pass protection on most downs, and tight end Vernon Davis has been frustrated by his increased blocking assignments this season. None of it has prevented those 19 sacks, but the 49ers believe the total will at least slow once they get comfortable in Martz's scheme.

"Our job is to block them until the ball is gone," said right tackle Barry Sims, who was beaten for two sacks by New Orleans' Charles Grant last week. "Sometimes it gets out quick, and sometimes it doesn't. We've got to stay on those guys until the ball gets out, and sometimes it's harder than others."

Notes: The 49ers still haven't filled the roster spot vacated by CB Shawntae Spencer, who went on injured reserve last week. Nolan said San Francisco is in no hurry because whatever player they get wouldn't crack the lineup on game day. ... RB Frank Gore sat out of practice Wednesday to rest, but he'll return Thursday. ... LB Manny Lawson will miss Sunday's game after straining his hamstring in New Orleans. ... RT Jonas Jennings is still at least one week away from returning from his shoulder injury.