The third down conversion rate used in every NFL broadcast and a primary basis for evaluating a team's effectiveness on offense is misleading, according to Brian Burke from Advanced NFL Stats.
In his weekly piece for the Washington Post Burke walks through the numbers to demonstrate why Skins fans shouldn't worry overmuch about the team having the league's lowest third down conversion rate.
Burke points out that if you look at the full series of downs -- including first and second down -- Washington is right at the league average in converting a first down. In other words, they're moving the chains on first and second down more frequently than other teams. They'll still want to improve on third down, but the situation isn't as dire as "worst in the league" sounds.
Burke also delves into play-calling strategy, suggesting that teams in general should call more passing plays on first down instead of trying to run the ball to get a more "manageable" third down opportunity.