The correlation between recruiting classes & AP rankings

We at UGASports have found over the years that class recruiting rankings are a good prelude as to how the final AP poll will look.

Following the recent release of the final AP poll for the 2020 season, we've compiled an updated analysis.

Beginning with Rivals’ initial team rankings in 2002, and for each subsequent year through 2020, we awarded “Rivals points” as conducted for the AP Poll. We allocated 25 points for a No. 1 team recruiting ranking, 24 points for a No. 2, etc. The result was Rivals’ 19-year team recruiting rankings (below left). Likewise, for the final AP Poll beginning in 2002 and through the recently released poll, we awarded points as mentioned, resulting in what is the final AP Poll’s 19-year rankings from 2002 through 2020 (below right):

Beyond the top 10, but for the FBS overall, is there any type of relationship between the Rivals team recruiting rankings and the final AP rankings?

Granted, there are the likes of Oregon, Wisconsin, and Boise State—FBS programs that have somewhat defied, over the last two decades, any correlation between recruiting rankings and final polls. Then there's the opposite extreme: Florida State, Tennessee, and Miami (FL). Still, these programs are only outliers. For the vast majority of FBS programs, there’s a high correlation between where a particular team ranked in recruiting classes, and where the same team ranked in the final AP Poll.

We’ve explained the correlation coefficient here before. Here it is again, in a nutshell: It’s a number between −1 and +1 calculated as to represent the dependence of two variables or sets of data. The nearer the coefficient is to -1, the more negative the correlation between the two sets of numbers. The closer the coefficient is to +1, the more positive the correlation between the two sets of numbers.

In this case, the two sets of data are the point totals for the Rivals recruiting rankings and the AP Poll over the last 19 years for all FBS programs, resulting in a correlation coefficient of 0.820, or what is considered a very strong relationship.

For the notion that perhaps it takes a year or two for a recruiting class to fully make its impact on the field, we also staggered the measuring of the two data sets (e.g., a one-year stagger didn’t measure the two sets straight up—both sets from 2002-2020—but rather measured the Rivals recruiting rankings from 2002-2019 staggered with the AP Poll from 2003-2020). A one-year stagger resulted in a correlation coefficient of 0.810; a two-year stagger (measuring the Rivals recruiting rankings from 2002-2018 staggered with the AP Poll from 2004-2020) yielded a 0.788.

In addition, realizing the smaller the sample size, the less likelihood of a strong relationship between the Rivals recruiting rankings and AP Poll, we compared the two sets of data for just the last six years. Measuring the Rivals recruiting rankings from 2015-2020 with the AP Poll over the same time period resulted in a correlation coefficient of 0.785—again, a very strong correlation/relationship.

Finally, since essentially only Power Five schools have finished in the top 25 in team recruiting rankings, we measured just the 65 Power Five schools. This resulted in a correlation coefficient of 0.787 over the last 19 years, and a 0.751 from 2015-2020.

Seemingly, no matter the sample size (number of years), or if there is a one- or two-year stagger—and even for the most extreme comparisons—there’s a high correlation (higher than .725 in every case) between where teams ranked in recruiting and where the same teams ranked in the final AP Poll.

So, how predictive are team recruiting rankings?

Well, when it comes, at least, to the Rivals rankings, they are quite relevant and of much significance, considering the rankings are a strong to very-strong indicator of where teams will ultimately finish in the AP Poll.