Merry preseason, everyone. It’s been a long offseason, but football is finally gearing up again and to celebrate I’m rolling out a new series on TSR entitled “2010 NFL Question Marks,” where I discuss one or two of the biggest concerns that teams have heading into the new season. Granted, some teams have more issues than others, but I’ll primarily be focusing on the biggest problem areas. Today I’ll be discussing the issues the Dolphins have had on their O-line thus far in preseason.

Had I wrote this piece before the preseason started, I would have written it about the Dolphins’ free safety position. But considering how good Chris Clemons has looked this offseason, it would be a reach to say that safety will be a big issue for Miami in 2010. (Especially when the ultra-productive Yeremiah Bell remains the starter at strong safety.)

After watching their first three preseason games, the biggest question the Dolphins’ faithful should have is what happened to the offensive line? Once considered a strength because of how well the team could run the ball, Miami’s O-line has be incredibly suspect thus far.

Jake Long and Vernon Carey remain entrenched at the tackle positions, while Richie Incognito and John Jerry are the projected starters at left and right guard, respectively. Joe Berger is slated to start at center after beating out Jake Grove this offseason.

The biggest problem is at the two guard positions, where Incognito and Jerry haven’t been good in pass protection or run blocking. Both are getting shoved backwards at the snap, which is troubling considering the Dolphins signed Incognito this offseason because of his power and drive in the running game.

The rookie Jerry has largely been a pleasant surprise, holding off Nate Garner, Cory Procter and Donald Thomas for the starting right guard spot. But despite his size (6’5”, 332 pounds) and strength, he has gotten pushed around at times this preseason. It’s fair to note that he is switching positions after playing tackle at Ole’ Miss, but given that the Dolphins expect him to start, he needs to continue to make strides so the run game doesn’t suffer.

At center, Berger is a fine spot starter and is versatile to play multiple positions along the line, but it remains to be seen if he can be an effective full-time starter. And considering he beat out Grove with minimal effort this offseason says nothing for Grove’s ability to reclaim the starting job, even after the Dolphins signed him to a $30 million contract in 2009.

The tackle positions are less of a concern, although Long still needs to improve his pass protection because he has problems with speed rushers. Carey is coming off a great ’09 campaign, although it’s worth nothing that his play dipped towards the end of the year while he was dealing with knee and back injuries.

Granted, some will point out that it’s only preseason and they’re right. These kinds of problems have a way of ironing themselves out during the season and given how good the Dolphins’ O-line has been over the last two years, maybe there’s nothing to worry about.

But here are the Dolphins’ rushing yards per game this preseason: 50, 83 and 46, with that last figure coming when the starting unit played the entire first half and some of the third quarter.

Again, maybe the O-line will pick up its play once the games start counting for real. But seeing as how the Dolphins have only averaged 60 yards per game on the ground this preseason, that’s a trouble sign – especially when you consider how vital the running game is to Miami’s success.