SANTA CLARA, Calif. - Justin Smith has set the bar pretty high for himself during his seven years in San Francisco.
So when he doesn't play very well against the run, as was the case for most of 2013, two assumptions can be made: his age is catching up to him, or, more likely, he's dealing with an injury.
Yes, 2011's First-Team All-Pro was, in fact, dealing with a shoulder ailment last year. He was on the injury report starting Week 3 and had the strength zapped from his left arm. But it didn't prevent him from starting all 19 games, including the playoffs, and earning Pro-Bowl recognition for the fifth straight season.
Smith, 34, is healthy now after offseason shoulder surgery, and playing at a level akin to what he's used to, like when he was a defensive player of the year candidate three years ago.
"I can use my left arm this year," Smith said. "I guess that’s a big plus."
The 49ers are second in the NFL in rushing defense, allowing an average of 69.8 yards through four games. And they are looking to keep that number low with Chiefs' speedster Jamaal Charles coming to a sun-baked Levi's Stadium Sunday. Last week, they held former rushing champ LeSean McCoy to just 17 yards on the ground.
Charles accounted for 108 total yards and three touchdowns in last Monday's 41-14 drubbing of New England. The Texas alum has averaged over 5.9 yards per carry in three of his first six seasons, and never less than 5.0 in his career. This season, he's averaging 4.3 while dealing with an ankle injury that kept him out of Week 3's win over the Dolphins.
"(The Chiefs) run at the edges, they do lots of insert blocks when they try to get in the middle and really spread your defense inside. They have a really good running scheme," Smith said. "...We’re going to have a big challenge in front of us."
Smith has strung together a month of good health for the first time since San Francisco's Super Bowl run in 2012, when he sustained a torn triceps injury in a December win over the Patriots. It caused him to break his consecutive-start streak that dated back to his rookie season in 2001 with the Bengals. He missed the 49ers' final two games in order to be ready for the divisional round against the Packers.
Smith wasn't the same player when he returned. Both he and Aldon Smith, who was playing with a torn labrum at the same time, went sack-less in their three postseason games. The duo combined for 22.5 during the regular season.
This year, Smith is responsible for three of the team's five sacks and is back to being the team's best run defender along the defensive line.
"(Smith's) someone I watch so much," coach Jim Harbaugh said. "He’s always playing at such a high level. Your eyes go to him as you’re watching the game. There’s just so much energy and aggressiveness the way he plays the game. It always looks good to me."
Smith is making plays when his team needs them. Last week he recovered a fumble and drilled Eagles quarterback Nick Foles as he threw a pass that ended up in the hands of Antoine Bethea. And when he wasn't drilling Philadelphia's QB, Smith was making him incomfortable in the pocket, playing a part in Foles' worst outing of the young season. The Eagles offense, that came in as one of the league's best, was shut out and the 49ers won 26-21.
Without Aldon Smith, who has five more games remaining on his nine-game suspension, San Francisco's pass rush has been lacking. The 49ers' sack rate of 3.27 percent of opponents' passing plays ranks fifth-worst in the NFL. Their inability to disrupt the quarterback played an important role in losses to the Bears and Cardinals.
"You can always rush better," Smith said. "That’s going to be week in and week out, (we are) always looking at ways we can take advantage of some of the protections we’re getting."
Sunday provides the unique task of trying to sack a former teammate.
Alex Smith comes back with the Chiefs to play the 49ers in a regular season game for the first time since being traded to Kansas City in the spring of 2013.
"It’s funny to be watching Justin on tape, and Patrick (Willis) and those guys that I played so long with," Alex Smith said this week.
"It’s tough to find much there. They’re a stingy defense. They’re physical up front. They’re smart. They’re well coached. Certainly a good challenge this week."
After squaring off against each other in five training camps, the Smiths will finally compete in a meaningful game.
"We know Alex really well. We got a lot of respect for him," Justin Smith said. "I think from his side and our side ... once the game starts it will be business as usual."
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