Quinn set the Rams' franchise record with 19 sacks last year. The fourth-year veteran has yet to record a sack this season. In fact, rookie defensive tackle Aaron Donald has the Rams' only sack.
"Numbers don't tell the whole story," said Staley, who will be lining up against Quinn most of the time Monday night in St. Louis. "He looks pretty good. He has a fast first step and uses his speed to his advantage. He's also added to his change of movement."
Quinn has drawn extra attention this year, especially with defensive end Chris Long out with an injury. Just don't tell Staley that Quinn is not as effective as he has been.
"They're pass rush is very good," he said. "Those numbers are misleading when it comes to sacks. There's pressure, there's hits and there is just being disruptive."
Quinn has nine quarterback hits and five quarterback pressures this season, an indication he's getting penetration. The Rams also own the best pass defense in the league.
"When you watch the tape, the quarterback is getting rid of the ball or something happens or he just dishes it, it's just getting out of his hand," 49ers offensive coordinator Greg Roman said. "We will not be lulled into that trap because all you've got to do is watch the film. (Quinn) is playing better than he did last year."
Staley anchors an offensive line that has been in flux early in the season, with a few setbacks leading to personnel changes. The line has gotten better and Staley said they played their best game Sunday in a win over the Kansas City Chiefs.
"We made great strides, especially in the running game," he said. "The other stuff we just have to deal with. Last week was a good building block."
This week's trip to St. Louis begins a stretch of road contests in four of the next five weeks.
"Any time you are on the road is a challenge because of the crowd noise," Staley said. "We're good at the silent count and we trust our center to snap the ball at the right time."
Wide receiver Anquan Boldin thinks it's even more than dealing with the noise.
"It's a chance to see what we're made of," Boldin said. "It's a chance to see what kind of players we are. On the road, we take an 'us against the world' mentality. We play our best when we feel that way."
Boldin criticized the officiating the last time the 49ers were on the road: a loss at the Arizona Cardinals. He has no complaints about the officials the past two weeks at home.
"It's been fair the last two weeks," he said. "Maybe we're getting better officiating crews. All I wanted to say was that whether you call a bad game or a great game, just call it the same both ways."
NOTES: The 49ers signed WR Kassim Osgood to a one-year deal. To make room on the roster, the team has released QB Josh Johnson. Osgoods been released and resigned three times this year. .. Defensive coordinator Vic Fangio said CB Perrish Cox has blossomed this season. "He's got good instincts as a corner. This is his first opportunity, at least with us, to have extended action as a corner. He's taken full advantage of it." ... Boldin has six career 100-yard games against the Rams, his most against any team.
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