SANTA CLARA -- Justin Smith says his surgically repaired triceps is "almost 100 percent." The looming question now is whether his 49ers career is almost complete.

Smith, the mainstay of the 49ers' defensive line, is entering the final year of his contract, at a $7.5 million base salary. He has talked about wanting to play a couple more years, but the 12-year veteran fears his future will be impacted more by the NFL's aversion to aging players than by last season's injury.

"At my point in my career, nothing's a given, nothing's a guarantee," Smith, 33, said Wednesday at minicamp. "They don't like old guys anyway for football.

"So I'm going to enjoy this year, do the best I can this year, and hopefully it's enough for us and the team, and we'll get it done."

Smith's streak of 185 consecutive starts ended after he partially tore the triceps in his left arm Dec. 16 at New England. Sidelined for the next two games, he struggled to regain his form in the playoffs and Super Bowl.

Smith's participation in the offseason program -- which concludes Thursday -- has consisted of weight-room work and individual conditioning. "I'm real close, feel good about it," Smith said. "(We) still have about six more weeks (until training camp), so I should be right on schedule."

Smith and his teammates also face a mental hurdle from their 34-31 Super Bowl loss to the Baltimore Ravens. It's a disappointing feeling he compared to the 2011 season's exit in the NFC Championship game.

"You can either let that tear you down mentally as a team or build you up," Smith said. "I think we're taking the build-you-up approach and realizing what needs to be done to get there."

To help Smith and Ray McDonald ease their workload as the starting defensive tackles, the 49ers signed Glen Dorsey in free agency and drafted Tank Carradine and Quinton Dial. Also in the mix are Demarcus Dobbs and Will Tukuafu, who saw first-team snaps while Smith and McDonald missed Tuesday's team drills. "They have the pantry full," Smith said. "There's definitely some guys worthy of some more reps."

  • The St. Louis Rams' secret for success against the 49ers last season has been unveiled and corrected, thanks to safety Craig Dahl, who left the Rams as a free agent and signed with the 49ers in March. The Rams apparently knew the 49ers' offensive intentions while losing neither of their 2012 meetings, tying 24-24 at Candlestick Park on Nov. 11 before posting a 16-13 overtime win in St. Louis on Dec. 2.

    "We had a few tips off of film we were able to differentiate between run and pass early," Dahl said. "So that kind of gave us an added benefit on defense. ... Different personnel and different alignment stuff really were the big keys as far as giveaways."

    Dahl said those offensive tells were already addressed by the 49ers' coaches before they debriefed him once he signed in March. Dahl, first-round draft pick Eric Reid and veteran C.J. Spillman are rotating this minicamp at Dashon Goldson's former spot as the first-team free safety.

    In response to Dahl's comments, Rams cornerback Cortland Finnegan tweeted that Dahl "is lame and weak for that" and now the Rams' offensive players "know who to go at."

  • Harbaugh said he made a mistake last year when he didn't use the NFL's injured-reserve exemption that would've allowed linebacker Parys Haralson to be activated late in the season. "He could've come back and played, because he was healthy and ready to go mid- to late-December," Harbaugh said of Haralson, who was placed on injured reserve shortly after tearing a triceps in an August exhibition.

    Haralson has been taking first-team snaps at outside linebacker while starters Aldon Smith and Ahmad Brooks rehabilitate from offseason shoulder surgeries.

  • Tight end Cameron Morrah was released and replaced on the roster with former Raiders wide receiver Brandon Carswell, who impressed as a punt returner last month during tryouts.

    Carswell injured his right knee less than an hour into his first practice. He had his knee wrapped in ice and watched practice for an hour before walking off the field.

  • Running back Marcus Lattimore, whose rookie year is in doubt because of a 2012 knee injury, ran well under a trainer's supervision between the two practice fields. Lattimore also played a short game of catch with general manager Trent Baalke.

  • Defensive coordinator Vic Fangio on British defensive lineman Lawrence Okoye: "He's got a lot to learn. Guys play pee-wee football, high school football, college football for a reason, and he hasn't."

    Staff writer Jimmy Durkin contributed to this report.