49ers cut free-agent pickup Darnell Dockett

SANTA CLARA - Darnell Dockett, who was signed in March to add some veteran punch to the 49ers’ pass rush, was released Friday as the 49ers began trimming their roster to get to 53 players.

The longtime Cardinals defensive end missed the 2014 season because of an ACL injury that occurred last August. But he took part in the 49ers’ practices and seemed earmarked to be a third-down specialist on the left side of the defensive line. Dockett, 34, said he was happy in that role.

“At this point, my career is in a good organization’s hands,” he said last month. “And I want to do everything I possibly can to put this team back on the top of the map. I want to be a part of it, and I want to make sure that we have an opportunity to be in the playoffs when everyone thinks that we don’t have a chance.”

Dockett, who is in his 12th season, missed Thursday’s preseason finale with a rib contusion, an injury he revealed this week via Snapchat when he identified it as a “cracked rib.” Jim Tomsula later clarified that the damage was to Dockett’s cartilage and was not severe enough to keep him off the field during the regular season.

At one point in his career, Dockett was the 49ers’ public enemy No. 1, and he loved to use social media to nettle both 49ers players - tight end Vernon Davis was a frequent target - and their fans. Tomsula was a longtime admirer from the opposing sideline, and he often would chat with and congratulate Dockett after games. When the Cardinals released Dockett earlier this year, Tomsula and the 49ers pounced.

Friday’s cuts also included safety Craig Dahl and guard Joe Looney, both of whom have been contributors in recent years, as well as veteran linebacker Philip Wheeler, who recently returned from a hamstring injury.

The 49ers are replacing two 30-something defensive ends, Ray McDonald and Justin Smith, this offseason. Glenn Dorsey, 30, is slated to start on the left side of the defensive line while third-year player Quinton Dial will play on the left.

Dockett has 40½ sacks over a 10-year span. The rest of the players on the line are young and unproven. The group includes Tank Carradine, Tony Jerod-Eddie and first-round pick Arik Armstead.

Considering that Armstead also plays on the left side - as does Jerod-Eddie - Dockett’s ouster likely heralds more snaps for the rookie. Armstead played 58 snaps in Thursday’s preseason finale, more than any other 49ers defender.

Dockett said last month that Armstead compares favorably to similarly sized defensive lineman Calais Campbell, a former teammate with the Cardinals.

“Some guys come in, being a first-rounder, and they think they know everything,” Dockett said. “He’s not like that. He asks questions and he wants to learn. And he’s very humble. That’s what I really like about him the most.”

The 49ers signed Dockett to a two-year, $7.5 million contract in March, a week after the Cardinals released him. He would have earned a $250,000 roster bonus had he been on the team next week.