As a skins fan:
I think the continuity and health of the line is a huge factor - similar to the Giants when they actually had a running game with Tiki/Jacobs.
I know other than Silverback(TWilliams) most of the other linemen can be seen as "scrub castoffs", truthfully they're better then they get credit for.
Kory Lichensteiger would allow some push his first year with us but would never really give up full penetration. In the last year-in-a-half though he's really been "on", without question our second best OL.
Montgomery does his job well, better than you would think originally - actually reminds me of Doug Free's surprising rise out of nowhere but w/o the 2nd year decline.
Chester is the prototypical "solid" guard, he doesn't get beat often but hes not going to pancake or road-grade people much either.
Polumbus is by far our weakest link on the OL. What sucks is that hes actually beast at run blocking(which is why we can still run to both sides - not just our strong side with Williams). He's mediocre as a pass blocker though. He can hold up against the midlevel-to-good DE's in the league but he gets eaten up alive by elite pass rushers - especially speed guys.
Another factor is that Shanny stashes multiple solid OL backups that can fill in when injuries occur. Something the cowboys don't - after their first line depth it can get scary but luckily Romo's mobility and quick release helps a lot of the Cowboys OL shortcomings.
After the OL I think its much more Alfred Morris factoring in than RG3. It's a travesty that Shannys mantra of plucking RB's out-of-nowhere kind of stigmatizes Morris as just another back. Trust me there are periods in games where Griffin sputters on offense yet Morris just keeps on moving the chains whenever he's called upon. People will continue to think it's Griffin that opens everything up for Morris but even the games where Griffin was injured or out Morris just kept on pounding away. There's a reason he ended up FAU's all time leading rusher - hes just that prototypical late round small school diamond, just like Romo.
On a sidenote: I know that many of my Skins brethren love to wallow in the boys demise and laugh at most of their players' plights - i.e. Romo's contract etc. I thought it was a necessary signing by you guys, not just because Romo's got the tools of an elite QB but because Dez Bryant is on the verge of destroying the NFL. As AZ showed a few years ago, a team with an elite weapon at WR(Fitz) with a hot QB(Warner) can carry an otherwise mediocre team deep into the playoffs. Now look at Fitz without a QB to get him the ball.
Trust me I know that in national-view there was tons of attention on all the great rookie qb's last year, Peyton Mannings comeback, AP's record chase, Megatrons record, Ray Lewis's retirement and the Jets unraveling - lots of things going on last year. Whats the one thing, just one little thing that quietly got slipped under the rug last year? The fact that Dez Bryant played like a man possessed in the second half of last year. The fact that Dez had almost 900 yards and 10 TDs from week 10 on - with a broken finger no less. I'm a big fantasy guy and I only have Megatron rated about him this upcoming year. When Dez says he thinks he can be the first 2000/20 WR.. I ::shudders:: believe him, trust me the lightbulb has been turned on ladies and gentlemen. Many people probably weren't paying attention last year but I was. Dez is going to be DISGUSTING this year.