The Seahawks used a very unique (for them) gameplan versus the Rams, a departure from the style that they normally play in the last few seasons. It almost worked. Despite only completing one pass downfield of over 10 air yards, Russell Wilson finished 32 of 41 in passing, many of these short passes left the Seahawks in 3rd and very short.
The Seahawks found themselves in 3rd and 1 five separate times (I can't recall a game in recent memory with so many of this distance) and they converted all of them successfully via running back run. They also converted a 3rd and 2 via the run.
Seattle also did a good job staying in very manageable 3rd down situations using this short passing game - the median Down and Distance for the twenty 3rd downs they faced (this is very high for the Seahawks) was 3.5 yards.
Again, I can't recall a game in the last few years where Seattle faced twenty 3rd downs.
The Seahawks were very unsuccessful in the passing game on these 3rd and manageable passing situations, and a sampling of these include:
-- 3rd and 3, Pass complete to Doug Baldwin for 2 (the 4th and 1 converted via FB dive)
-- 3rd and 4, Intercepted by Trumaine Johnson
-- 3rd and 6, Sack by Aaron Donald
-- 3rd and 2, Incomplete to Marshawn Lynch
-- 3rd and 2, Pass complete to Jimmy Graham for 1
-- 3rd and 8 (this is not "manageable," but threw it in here), Sack by Aaron Donald
-- 3rd and 4, Incomplete to Doug Baldwin
-- 3rd and 4, Incomplete to Jermaine Kearse (this is the DPI on Kearse in endzone)
The Seahawks did convert two 3rd and 7s in the 4th Quarter: One where Wilson scrambles for the 1st down, and the other is the touchdown pass to Jimmy Graham.
Overall, when excluding kneeldowns and (in this case generously), giving the Seahawks credit for converting via penalty, they converted 9-of-19 3rd down opportunities (47%). This is quite good on the surface, but again -- is largely due to being excellent running the ball on these 3rd and short situations. The passing game needs to pick it up in the 3rd and 2 to 3rd and 6 yards to go area.
I don't think 50% in these scenarios is an unreasonable goal to shoot for.
Here's the chart.