The San Francisco 49ers' offensive line has been a consistent weak point for much of the season. It's been a big surprise to just about everybody involved, and it's not just because of the injuries felt along the line. To some extent that can be a factor -- cohesiveness is a huge part of offensive line play.
But at the end of the day, all of Joe Staley, Mike Iupati and Alex Boone have been soundly beaten and have looked clueless on the field. Boone and Iupati have been particularly bad (Boone was very bad against the Denver Broncos, despite an erroneous positive grade from some), with the latter being egregiously bad in the passing game more often than naught.
It's been rough. And things are likely only to get worse from here.
Marcus Martin has a ton of potential. I like him better than Daniel Kilgore as a starter for now and for the future. But if anybody was expecting Martin to come in and make this offensive line instantly better, they were probably hoping for too much. Again, Martin getting in there is probably good for the future of the team, but there's one thing that's been overlooked thus far:
Kilgore was the 49ers' best offensive lineman this season. He blocked better than the rest of them in pass protection and was serviceable in the run game. You could find Boone and Iupati standing there with nobody to block on multiple plays, but almost never for Kilgore. He always had someone to block and he rarely got beat.
I'm assuming that he looked a lot better than he was because he was playing next to some pretty under-performing guards, and there's always the chance that he'd come crashing back down to Earth, but he was solid. Martin is not going to come in and "fix" any problems, even if he out-performs Kilgore. The 49ers already had a good center and the line was still terrible.
The problems run much deeper, and it's probably going to get worse before it gets better. Thankfully, we've seen at least a few solid games from the line as a whole scattered throughout the season.