I'm not a fan who thinks his team has the worst line in the league. I see much worse groups every week. But I have a problem with their methodology. The Rams are 6 or 7 in their rankings, and I do know that isn't accurate.
The Rams stress short throws, and Bradford is super quick to check down. They also never get stuffed on runs. Few negative yardage plays there. But there also aren't any giant holes either. It's a low risk low reward offense that protects the line (and QB and WRs and RBs). Add to that they have played the Falcons, Jags and a banged up Cards team, none of whom can rush the passer, and the the stats look good.
When I think of a good offensive line, I think of Tom Brady vs ATL where he stands in the pocket for 8 seconds looking all over the field to throw, or SF cramming it down the Texans' throat.