Our 49ers.com training camp positional previews continue with a look at the 15 offensive linemen currently on San Francisco's roster. Each player will have the test of keeping up with and thriving in Chip Kelly's up-tempo offense.Returners: Trent Brown, Ian Silberman, Brandon Thomas, Andrew Tiller, Daniel Kilgore, Erik Pears and Joe StaleyNewcomers: Zane Beadles (Free Agent, Jacksonville Jaguars), Joshua Garnett (Draft, First Round, Stanford), Alex Balducci (Undrafted Free Agent, Oregon), Fahn Cooper (Draft, Fifth Round, Ole Miss), Colin Kelly (Free Agent, CFL), Blake Muir (Undrafted Free Agent, Baylor), Norman Price (Undrafted Free Agent, Southern Mississippi), John Theus (Draft, Fifth Round, Georgia)What we know:
Barack Obama hadn't even taken his seat in the Oval Office when Joe Staley became the anchor of the 49ers offensive line in 2007. The 28th overall pick that year was a Day 1 starter at left tackle and has yet to relinquish his iron grip on the job. Staley is on a current streak of five straight Pro Bowl seasons and 80 consecutive games played.
The stability that Staley has provided, at one of the most sought after positions in football no less, continues to be a luxury for San Francisco.
While other spots are up for grabs, there's a strong chance that Beadles will be starting at one of the guard positions in 2016. The team's free agent acquisition spent a bulk of the offseason program next to Staley at left guard, but the coaching staff could ultimately opt to move him to the right side of the football.What we'll find out:
Garnett showed during mandatory minicamp that he's capable of being a quick study in Kelly's offense. The team's second of two first-round choices in 2016 will push for a starting role as a rookie. Garnett played left guard as a senior at Stanford and will likely see reps on both sides during training camp. Where Garnett ends up being the most comfortable could have an impact on where Beadles lines up this season. Both guards are talented enough to play either position.
Kilgore is back at full strength after missing a majority of 2015 with a leg injury. He'll be a favorite to start at center, but Martin will also stake his claim to the job in August. Martin has made 22 starts at center over the past two seasons.
The marquee competition on the offensive line will take place at right tackle. Pears is the incumbent at the position having started all 16 games last season (14 at right tackle). Brown is another candidate to win the job having played well in his two starts in Weeks 16 and 17 last season. San Francisco's pair of 2016 draft choices, Theus and Cooper, could be dark horses to start as rookies.Quote of the offseason:
"As players, you never look at a season as a rebuilding season. It's a waste to guys like me, guys who are coming to the end of their career a little bit. You can't waste years rebuilding. I'm trying to win right now. We've got to do everything we can to win football games this year." – Staley on his expectations for 2016.