Well according to this, <a class="postlink" href="http://footballoutsiders.com/stats/ol2010" onclick="window.open(this.href);return false;">http://footballoutsiders.com/stats/ol2010</a>
Last year the Rams had the 10th "best" OL when everything was taken into account (opponents, aggressiveness, etc.).
This year, so far it's ranked 28th. <a class="postlink" href="http://footballoutsiders.com/stats/ol" onclick="window.open(this.href);return false;">http://footballoutsiders.com/stats/ol</a>
What's the biggest difference? Injuries, 1st and foremost. When both starting OTs get put on IR, their backup gets hurt. Then the center gets benched.
Quality of opponent. When you have to face a blitz happy Eagles, Packers, Saints teams, the best 4-3 DL in NFL the NYG, a top D w/ probably the best OLB pass rushing DeMarcus Ware, another top D against the Ravens. And yeah, even the Redskins have a good D. You gotta give credit to the opponent, in this case, veteran top opponents.
This line didn't do too bad against teh Browns/Cards. Not until PS guy Hughes went against Clemons did it become to unravel. IDK how much merit that website has, but it is kinda interesting.