If first down means everything, what does third down mean?

I linked to a Chris Brown post yesterday about the importance in the NFL of gaining at least four yards on a first down play.

… According to Dr. Massey, an assistant professor at the Yale School of Management, the ability of an NFL team to meet certain benchmarks on each down is one of the best predictors of whether a drive will be successful. When it comes to first down, he says, the magic number is four. That’s the number of yards Mr. Massey says teams need to gain on first and 10. Those that do, he says, are more likely to be successful in making a first down and keeping the drive alive.

I was curious to see how applicable this was to Georgia’s offense (billed as pro-style, right?) last season, so I thought I’d wander over to cfbstats.com and see what the statistical story told.

On one level, what it told was favorable.  Georgia averaged almost five yards per rushing attempt on first down and right at ten yards with each first down passing attempt.  Yet that translated into a fairly pedestrian set of results.  The Dawgs were eighth in the conference in total offense, eighth in first downs and fifth in time of possession.

Compare those results with Alabama, which ran an offense that was more similar to Georgia’s than any other SEC team’s.  The Tide ran and passed successfully on first down (in both cases, at a better rate than the Dawgs did) and wound up higher ranked in the SEC in total offense, first downs and time of possession.

But it’s third down that’s the real eye opener.  Alabama’s passer rating on third down was a respectable 158.47; Georgia’s was a sub-par 127.63.  The third down rushing figures have a similar gap in that ‘Bama was able to run the ball on average more than a half-yard per attempt than Georgia did.

Chris’ conclusion is worth considering here.

… I think the upshot of Dr. Massey’s analysis is that most first down playcalling is not good, and too often puts the offense in a bad spot. If you show me a team that is good on first down, I’ll show you a good offense. Indeed, the best offenses look at it like they are playing under Canadian rules: if you only have two downs to get a first down, you approach the problem quite a bit differently. Third down shifts the burden away from the defense to the offense; better to avoid as many third downs as possible.

As a percentage of total plays run, Alabama was in third down 18.21% of the time.  Georgia’s third-down percentage was 20.02%.  That may seem like a subtle difference, but the upshot is that the team which ran more total plays also ran fewer of them on third down.  Of such subtleties are more mediocre offenses born.