SANTA CLARA, Calif. — Six-time Pro Bowl centre Alex Mack is reuniting with coach Kyle Shanahan after signing a contract with the San Francisco 49ers.

The 49ers announced the three-year deal with Mack on Thursday, one day after agreeing to give left tackle Trent Williams a $138.1 million, six-year deal to remain in San Francisco.

Mack said the Niners were his top priority in free agency because he wanted to play for a competitive team with an offence that fit his skills.

“I know it’s a system I can be really good in,” he said. “It’s an offence, I know I could excel at. So it was to me a very good fit between a good team and a good spot with a good coaching staff and some place that I could be a good player.”

The deals with Williams and Mack go a long way to solidifying an offensive line that struggled in pass protection last season. The 49ers still could look to upgrade at right guard if they don’t want to leave that role to Daniel Brunskill or Colton McKivitz.

The 35-year-old Mack returns to the Bay Area after starring in college at Cal and having a successful run in Cleveland and Atlanta. He made the Pro Bowl six times, including four straight from 2015-18. He was also a second-team All-Pro in 2013, ’16 and ‘17.

Mack has a history with Shanahan, having played for him in 2014 when Shanahan was offensive co-ordinator in Cleveland and again in 2016 in Atlanta. Mack’s addition was a key part for the Falcons’ offensive improvement that season when they went to the Super Bowl to help Shanahan get the head coaching job in San Francisco.

“I’ve been on that offence before, so I’ve done those plays,” Mack said. “I know how it fits together. I enjoy running the ball. I also just know what goes into putting together an offence. I’ve been part of offences Kyle’s been part of it. ... It’s something I’m comfortable with. I know I’m good at it. I’m confident in it. I know I can do it well.”

Mack replaces the void created by injuries to Weston Richburg, who has struggled to get on the field after signing a five-year $47.5 million deal with San Francisco in 2018. Richburg had a season-ending knee injury late in 2019 and missed all of last season when he didn’t recover.

He reportedly had hip surgery recently and his chances of returning are in doubt.

That set the stage for the Niners to turn to the durable Mack, who has played all 16 games in 10 of his 12 seasons in the NFL. He missed 11 games in 2014 with a broken leg and the final two games last season with a concussion and then a week on the COVID-19 list.

“We are excited to add another Pro Bowl player to our offensive line,” general manager John Lynch said. “Throughout his career, Alex has been a model of consistency. His leadership and high character will be felt throughout our team and community.”

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