One plus for the 49ers in 2018 will be the return of guard Joshua Garnett.

Garnett, a first-round pick of the Niners out of Stanford in 2016, was a physical, elite-level run blocker in college but struggled in his first season in the NFL. Then, he was lost for the year in preseason to a knee surgery. Guard remains an area of need for San Francisco, so Garnett’s return to health and another year of learning could give the offense a boost – if he makes some improvements.

As a rookie (starting 11 of 15 games he played), Garnett had troubles as both a pass- and run-blocker as graded by the analytic website Pro Football Focus. In fact, Garnett’s grade was lower than that of Zane Beadles, the often-criticized 49ers journeyman who’s filled in at both guard and tackle. Despite his struggles, Garnett is a smart, strong offensive lineman who should get better with experience.

The 49ers could have used Garnett last season, but general manager John Lynch decided to not activate Garnett to allow him to take the entire year off to transform himself physically for better performance in 2018. The 49ers have asked Garnett to lose weight (he was drafted at about 325 pounds) and become more agile.

“We took a long-term view with Josh,” Lynch said in late November. “So we made that decision, which was a hard one (to stay on injured reserve), but we certainly hope he responds well. He’s working his tail off. He’s done a great job of really changing his body composition.”

Garnett told David Lombardi of The Athletic that he’s worked to cut his body fat while increasing his flexibility. That should help him play more effectively in the 49ers’ zone-blocking scheme under head coach Kyle Shanahan. Garnett told Lombardi he’d like to be in the 305- to 310-pound range for the 2018 season.

“The Zack Martins (Dallas Cowboys), the David DeCastros (Pittsburgh Steelers), all the guys who are great NFL guards right now, none of those guys are 325,” Garnett said. “All of those guys are 300-310 and really athletic and really fast. That’s what I’m trying to model myself after.”

In mid-December, Garnett posted a photo of himself on Instagram lifting weights with the caption: “Process, process, process, process, process, process, process, process, process, process, process, proooccceeessss #49ers, #niners #ninergrang #ninerempire.”

Garnett told Matt Barrows of the Sacramento Bee that he’s excited by the changes in his body, the result of a better diet and strength training. He can’t wait for organized team activities this spring.

“I feel stronger than I’ve ever been, more lean than I’ve ever been,” he told Barrows late during the 2017 season. “ … I already feel like I’m in the best football shape I’ve been in in years. So I’m like, ‘Jeeze, if I can continue to do this, then I’m going to be a monster by the time OTAs come.’ ”