Six degrees of college football

With 124 teams and 12 scheduled games, FBS college football teams play less than a tenth of the national competition. This problem is compounded by scheduling incest - 2/3 to 3/4 of almost every team's schedule is filled with the same handful of conference opponents. As a result, we depend heavily on inter-conference play and the transitive property* to evaluate teams. But with only 3 or 4 out-of-conference games for most teams, it can often take multiple games and multiple teams to connect any two teams, and the random variation that affects every game is multiplied many times over.

The chart below shows the number of 1st order (the teams play each other) and 2nd order (the teams play the same 3rd team) connections between conferences. Some conferences are paired with several 1st order connections: Big 10 and MAC, Sun Belt and SEC, WAC and MWC, for example. The number of 2nd order connections are more difficult to guess; for example, there are a large number of 2nd order connections between the ACC and MAC largely because they both play a lot of games against the Big East.

Looking at conferences with legitimate national title contenders, we quickly see where the scarcity of inter-conference connections can become a serious problem for selecting teams to play for the MNC. The ACC and Big 12 have 3 and 4, the Big 12 and Pac 12 have 1 and 3, and the SEC and Pac 12 have 2 and 2.

* A is 10 points better than B and B is 20 points better than C so A is a lot better than C, too.