A team's third-down success on offense often reflects more than just its ability to succeed on that down. Usually it's a function of how well the team plays on first and second down, as those plays determine whether you're trying to convert third-and-short or third-and-forever. Getting into third-and-long has been a problem for Seattle over the last two seasons, as we'll explain below (the Seahawks have averaged third-and-9 or longer in three of four games this season).
Through four games, Seattle has converted 18 of 35 times on third-and-9 or shorter. This includes 10/16 on running plays and 8/19 on passing plays. The Seahawks have converted five of 21 times on third-and-10 or longer. This includes 1/4 running and 4/17 passing.
A story I wrote in late November 2005, after the Seahawks had won seven games in a row, shows that the current numbers actually reflect improvement over the third-and long pace set through 11 games last seasson. To that point in 2005, the Seahawks had converted 50-of-93 times (.537) on third-and-9 or shorter, but only 5-of-46 times (.109) on third-and-10 or longer.
So, the Seahawks have converted 5-of-21 times (.238) on third-and-10 or longer this season, compared to 5-of-46 (.109) last season. PROBLEM IS, at their current four-game pace, Seattle will have 58 such plays after 11 games, up from 46 last season. They had 51 for ALL of the 2004 season.
The chart below shows Seattle's run/pass ratios by various third-down situations this season.