SANTA CLARA — Aldon Smith was a no-show in the 49ers locker room on Tuesday — just as he has been on the sack list lately.
Through 14 weeks of the regular season, Smith had 19? sacks, enough to join Houston's J.J. Watt in pursuit of Michael Strahan's single-season NFL record of 22?, set in 2001. Smith's campaign was exemplified by his performance against the Chicago Bears on Nov. 19, when he terrorized fill-in quarterback Jason Campbell and sacked him 5? times — a half-sack shy of Fred Dean's 29-year-old franchise record, and 1? short of Derrick Thomas' NFL mark.
A strange thing has happened in the past month, though. Smith stopped getting to the quarterback. Heading into Sunday's NFC championship game at Atlanta, he has gone four games without a sack, the longest drought of his young career.
Why the sudden drop-off?
Monday, 49ers coach Jim Harbaugh seemed offended by the very question.
"Why hasn't he gotten a sack every single game or two sacks every single game?" Harbaugh asked, an edge to his voice. "He's been effective. He's playing effective. That's good. It's what we want. We want to strive for perfection, keep chasing that. But you guys are pointing out every single spot that we haven't quite gotten there."
Others have theories. Some point to Smith's sore shoulder, which has put him on San Francisco's injury report leading up to the past seven games. Could he simply be worn down by a 16-game NFL season?
Others note the recent absence of defensive lineman Justin Smith, who missed 2? games with a torn triceps. It's accepted as fact that Justin Smith's strength and relentless effort take pressure off everyone around him, including Aldon Smith.
Here in Santa Clara, the consensus is that Smith hasn't slowed down at all. Opponents are simply game-planning around him.
"They're changing," 49ers safety Donte Whitner said. "They're chipping him, they're sliding protection to him, they're using two guys. When he and Justin run their little (stunt) game, everybody in the NFL is ready for it now. So it gets harder. When you get to the level that he's at, No. 1 in the National Football League for so long, they're talking about you in the meeting room. They're looking at you on film. They know where you are."
Defensive end Ray McDonald said that opposing quarterbacks are getting the ball out quicker, too, wanting no part of an Aldon Smith sack. Ricky Jean Francois, normally a backup defensive lineman, saw the adjustments clearly when he filled in for Justin Smith, who plays both defensive tackle and end.
"Teams have to respect him," Jean Francois said of Aldon Smith. "While Justin was out and I was on the same side as him, I'd see the frustration of what they gotta go through when you get the center or the guard, the tackle, a tight end or a running back in the back trying to chip him."
It's not like the 49ers' pass rush has dried up during Smith's sackless streak. Jean Francois and McDonald have two sacks each over the past four games. Nose tackle Isaac Sopoaga and linebackers Ahmad Brooks and Patrick Willis have one each.
To hear the Niners tell it, that isn't a reflection of teammates picking up the slack for a diminished Smith in coordinator's Vic Fangio's 3-4 defensive scheme. It's a direct result of all the attention Smith is getting.