Regarding primetime Overs covered on this excellent podcast, here's a theory on one contributing factor: scoring inflation is occurring due to rule changes and how officiating is implementing them, and with the greater scrutiny that comes with stand-alone primetime games, more first downs via penalty are driving scoring higher.
1st Downs via penalty are correlated with Over—59% of games with a team gaining 4 or more 1st downs via officiating are Over since 2008—and these games have been steadily increasing since 2008. They are way up in 2014. 2014 is on pace to see 77 games with 4 or more first downs via penalty, which would be more than double the total from 2009 and up 22% from the average of 2011-2013.
Primetime games in 2014 have featured a higher percentage of these "4 or more 1st down by penalty" games (35% vs. 30% for non-primetime games) and these penalty-rich primetime games have landed disproportionately Over, 9-2-1.
One theory, but this PT Over trend this seems too pronounced to be merely an aberration. Thoughts?