SANTA CLARA – The 49ers' wide receivers seem faster. The offensive line isn't allowing as many sacks. The quarterback isn't throwing as many interceptions.

All of which, offensive coordinator Mike Martz said Thursday, is a function of the team fully – and finally – understanding his offense.

"I'm excited," he said. "The guys are growing. They're getting on the same page. They're getting excited about playing. When you know what to do and you're sure about it, now you can compete. It's taken a little bit of time, but I think that's where we are."

Martz discussed a number of topics, beginning with quarterback Shaun Hill, who, according to Martz, struggled to learn the offense during the exhibition season. With that in mind, Martz expected Hill to come along slowly in his first few starts.

That hasn't been the case.

In fact, Martz credited Hill with reducing the number of sacks the 49ers have allowed in the past two games. The 49ers led the league in that ignominious category over the first half of the season. But with Hill making quick decisions and releasing the ball on time, the 49ers have allowed two sacks in the past two games and are now third overall with 36 sacks allowed.

"He doesn't hang on to the ball, and it's gone," Martz said. "There's no hesitation. That's why I'm a little surprised – you've got to really know what we're doing to do that."

Martz also spoke fondly of his young wide receivers. He said that rookie Josh Morgan is still dealing with a severe groin injury that likely will cost him several more games.

But with a healthy Morgan and second-year player Jason Hill, Martz said he has one of the swiftest receiving corps he's had since he was with the St. Louis Rams.

"We're faster than probably what I've experienced in the last few years," he said. "These guys are big and can get down the field well."

One fine day – One topic Martz refused to discuss was the $20,000 fine levied against him by the NFL this week for comments he made about the officiating during the team's Nov. 10 loss to Arizona on "Monday Night Football."

Following the loss, Martz was exasperated that the officials did not notify the 49ers' sideline that they would to move the ball back to the 2 1/2-yard line on the final play of the game following a review of the previous play. The referee announced the move over the stadium public-address system, but 49ers coaches said the announcement was drowned out by crowd noise.

Martz's most caustic remarks on the subject were to CBS Sportsline.

"We couldn't change the play," Martz said the day after the game. "We had to go with what we called. If it would've been at the 1, we would've made it. But they moved it and didn't give us any time. So what are we going to do? If they would've moved it to the 10, we still would've had to run the play that was called. We got screwed because of the spot, first and foremost."

Martz thought the play would be run from inside the 1-yard line, which is why he called a fullback dive. The game ended with the 49ers being stopped more than a yard short of the end zone.

Willis misses practice – Patrick Willis, the only defensive rookie last year to play every snap of the season, has yet to practice this week.

Willis missed Wednesday's session with a hip strain. He was feeling under the weather Thursday and missed practice again. Interim head coach Mike Singletary said neither issue was serious enough to keep Willis out of Sunday's game.

"He's got a little nick here and a little nick there," Singletary said. " … But he'll be OK."

Read Matthew Barrows' 49ers blog at www.sacbee.com/ninersblog.