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Too late to save 49ers offensive line?

The 49ers offensive line struggled their third preseason game, raising the question about whether or not significant changes are in store before the start of the regular season.

The Denver Broncos held the 49ers' first-team offense to three first downs in the first half in preseason game No. 3. That was as long as Colin Kaepernick played.

San Francisco's starting quarterback completed 2-of-5 for 13 yards, with both completions coming on a last-second drive in the first half culminating a field goal from Phil Dawson. Those were the only points San Francisco could muster in the first half. The 49ers wound up losing 19-12.

Aside from his two long runs combining for 53 yards on that possession, Kaepernick was held in check by the Broncos' talented defense. His legs were his only recourse, consistently having to run for his life from Von Miller, DeMarcus Ware and Co.

Pass rushers were constantly in the 49ers backfield, despite registering only two sacks on Kaepernick. One was a safety, when both players along the right side of the offensive line got beat on a passing play from the 49ers' 3-yard line. Right tackle Erik Pears couldn't handle a speed rush from Ware, while Antonio Smith out-muscled right guard Ian Silberman as Kaepernick tried to stretch the ball over the goal line to avoid the safety.

Kaepernick couldn't, and it gave the home team a 5-0 lead.

For the first time this preseason, head coach Jim Tomsula went with Silberman, a rookie drafted in the sixth round, in the starting lineup. That switch moved Marcus Martin from right guard to center, where he started eight games last season, in place of Joe Looney, who was relegated to the second unit.

The rest of the line featuring Joe Staley at left tackle, Alex Boone at left guard and Pears at right tackle, remained as it was in the first two weeks of the preseason. And after playing well in the preseason opener at right guard, former third-round pick Brandon Thomas has continued to work at left guard with the second team.

The lack of production along the offensive is alarming for San Francisco, considering Tomsula's had four weeks to piece together a starting unit. The clock is ticking.

Do the 49ers need to make changes? The results say so.

A few notes to consider:

--Boone has spent all of camp at left guard, after starting at right guard the last three seasons. When Anthony Davis retired, Boone was suddenly San Francisco's second-best offensive lineman. Conventional wisdom said Boone, a former tackle at Ohio State, would move one spot to his right and replace Davis, book-ending the offensive line opposite Staley. Instead, the 49ers moved Boone to left guard because transitioning to left tackle would be easier in case of an inury to Staley, Tomsula and offensive coordinator Geep Chryst said.

--General manager Trent Baalke said in the spring Thomas was drafted with replacing Mike Iupati in mind, after he left for Arizona in free agency. Thomas began the preseason at right guard before moving back to the left side over the last two weeks. Boone at left guard has blocked Thomas from playing there with the first unit.

--Prior to this week, Martin had been working at right guard with the starters. It's the first time he's played on the right side of the offensive line since high school. He started his career at USC at left guard before moving to center, where he started eight games as a rookie in place of the injured Daniel Kilgore in 2014. Martin got his first start of the preseason at center Saturday.

--Silberman had a good preseason before struggling against Denver Saturday, and reportedly during the week of joint practices. He was replaced late in the first half by newcomer Jordan Devey, whom the 49ers received in the trade for tight end Asante Cleveland from the Patriots. Looney, who knows all three interior line spots, played center with the second team.

With Kilgore out and Anthony Davis retired, a logical lineup to try would be:

LT Staley
LG Thomas
C Martin
RG Looney/Silberman/Devey
RT Boone

But that unit hasn't worked together in a practice or a preseason. With 15 days before the season opener, do the 49ers consider that drastic change? Time will tell. The next clue comes in Thursday's preseason finale against the Chargers.


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