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The San Francisco 49ers’ 1-2 start can be attributed to a lot of things. The massive number of penalties the 49ers have suffered is one of them. A tough road game against a double-digit win in another. Nothing, however, is harming the team more than injuries.

We all know about the issues that has hampered the defense. NaVorro Bowman still is recovering from an ACL tear last season, Glenn Dorsey is working his way back from biceps surgery and Tramaine Brock has missed the last two games with an injured toe. That’s not even getting into Aldon Smith’s suspension.

The most harmful injury, however, might not be on defense at all. The 49ers desperately need right tackle Anthony Davis back in the lineup.

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Davis is suffering from a left hamstring injury, after missing most of camp recovering from shoulder surgery. The 49ers had hoped that he would have been ready for the Arizona game, but there has yet to be any sign of him in 2014.

In his place has been Jonathan Martin, the ex-Dolphin. Martin's play has been less than exemplary. In three games, he has earned a Pro Football Focus grade of -2.1 (subscription required), and that’s including a positive grade for his effort against the Dallas Cowboys.

But over the last two games, Martin’s grade has been very poor (-4.4), as he struggled particularly in run blocking. The 49ers have struggled running behind the right side of the line have so far this season:

49ers Rushing by Direction in 2013 and 2014 Direction Carries ('13) Yards Avg Carries ('14) Yards Avg Left End 86 313 3.6 16 63 3.9 Left Tackle 35 182 5.2 6 24 4.0 Left Guard 27 107 4.0 6 50 8.3 Middle Left 47 194 4.1 4 8 2.0 Middle Right 52 198 3.8 8 27 3.4 Right Guard 40 158 4.0 5 12 2.4 Right Tackle 52 157 3.0 5 10 2.0 Right End 92 431 4.7 17 65 3.8 Pro Football Focus

While Martin’s fine as a backup, he’s not close to being in Davis’ league. Martin grades out as the 45th-best tackle in the league, a far cry from the pair of top-30 tackles the 49ers are used to.

But it’s not just the run blocking. Martin is the only 49er offensive lineman whom Pro Football Focus has charted as allowing more than one sack (subscription required), and his four quarterback hurries allowed aren’t great, either. Colin Kaepernick’s ability to run out of trouble has spared Martin further hits on his grade, but you can only have your quarterback running for his life so often before it starts becoming a serious issue.

Martin was also responsible for one of the more damagin penalties against Arizona: He was called for clipping on a key 3rd-and-8 play at the beginning of the fourth quarter, which pushed the 49ers far enough back that the Cardinals were able to block the ensuing 45-yard field-goal attempt by Phil Dawson. It doesn't qualify as the most painful penalty the 49ers suffered on the day, but it just shows that Martin has been subpar in a variety of different aspects.

Coach Jim Harbaugh has been reluctant to come out and criticize Martin for his poor play. After the Chicago game, he was specifically asked about the play of Martin, and dodged the question:

We could talk about a lot of guys. There's some really good things and things that we'll look to improve on. We all kind of fall into that category right now after this game. We all feel like we have fingerprints on it. Some really good things were done by Jonathan Martin, by our offense, by our defense, by our special teams. Other things we need to improve on.

Harbaugh is certainly right that there’s plenty of blame to go around for the two-game losing streak, starting from the play-calling and going all the way down to the play of key reserves. The biggest fix available on the horizon, however, is replacing Martin as soon as Davis is ready to go.

One option the 49ers could consider is moving Alex Boone over to right tackle and plugging Joe Looney back in at right guard, but that’s not ideal, either. Looney’s grade against Dallas, the one game he saw significant playing time in, was -2.3 (subscription required), so it’s not like he’s been lighting the world on fire this season, either.

The good news is that Davis should be back very soon. It’s a day-to-day issue at this point, and there’s a good chance Davis returns to practice this week. He’s been working with the strength and conditioning coach these past couple weeks, according to Matt Maiocco, and he’s gearing up for a full return.

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It’s worth noting that Alex Boone did not get action in his first game coming back from his offseason holdout. It’s probable the 49ers would take a similar route with Davis, allowing him to have a week of practice before coming in as the full-time starter. That probably means Martin will at least get one more start against the Philadelphia Eagles this Sunday, where he’ll have to take on the likes of Connor Barwin and Cedric Thornton.

It’s not exactly the most groundbreaking analysis to say that there are a number of 49er players who have to perform better, especially when the team sits at a disappointing 1-2. None of the 49ers' current problems are unmanageable, but there are a number of them and they come in different shapes and sizes.

Improving the play of the right side of the offensive line is one of these concerns, and it starts with Jonathan Martin. Of all of the woes the 49ers are facing so far in 2014, the play at right tackle seems the simplest to fix. San Francisco fans will just have to keep sitting and waiting for all of their starters, including Anthony Davis, to get back and hope that the team doesn’t dig too deep of a hole before that happens.

Bryan Knowles is a featured columnist for Bleacher Report, covering the San Francisco 49ers. Follow him @BryKno on twitter.