ENGLEWOOD, Colo. --Given what the 49ers' defense has done without this year, their lofty stature in the league's defensive rankings is remarkable.
- Yardage allowed per game: 287.2, second
- Yardage allowed per play: 4.9, fourth
- Passing yardage allowed per game: 207.3, second
- Yardage allowed per pass play: 5.4, third
- Percentage of pass plays to gain first downs:30.0, fourth
- Rate of passes of at least 20 yards allowed: One every 19.2 pass plays, first
- Rushing yardage allowed per game: 79.8, fifth
- Yardage allowed per rush: 3.9, 10th
That's from a defense that has yet to field linebacker NaVorro Bowman or suspended outside linebacker Aldon Smith, the unit's best pass rusher. Sunday night, it will be without Patrick Willis, ruled out Friday because of a toe injury.
The injuries and suspension of Smith hindered the pass rush, the one area of defense in which the 49ers lag. Their sack rate of one every 23.0 pass plays ranks 21st in the league. But defensive linemen Ray McDonald and Justin Smith can generate pressure, even though sacks have been rare.
"I was with both those guys in '08 and it hasn't changed," said Broncos Offensive Coordinator Adam Gase. "Up front, stout, and then just that whole group they have in the linebacking corps, they're physical as well. That front seven is a tough group to go against."
How tough it is without Willis depends on the growth of rookie Chris Borland, who is expected to be his replacement in the starting lineup. Borland dropped out of the first round last May because of concerns about his speed, but takes excellent angles and is a solid tackler, which makes up for it.
But outstanding coverage in the secondary allows the 49ers to hold opponents to a 55.9 completion percentage, the best in the league for a defense. The collective 73.7 quarterback rating of opposing quarterbacks ranks third.
Antoine Bethea and Perrish Cox have been the 49ers' two standouts in the secondary, although 2013 first-round pick Eric Reid and cornerback Chris Culliver have been solid, although Culliver comes to Denver off a game in which he allowed his first touchdown of the season.
"They can be great," said wide receiver Demaryius Thomas. "They have one of their cornerbacks leading the league in interceptions and he's running the ball a lot. Our main thing is to trying to do something to convert and get in the red [zone]."
But as the 49ers' overall numbers indicate, just getting to the red zone in the first place is a difficult task.