average for their time slot and channel. Also, I think consideration should be given for how many times teams are televised at all. Much easier for a team to have a higher viewership number if they're only televised twice per year on a network channel vs a team televised 9 times per year on a lower rated channel. Total number of televised games gives an indication of how TV execs view the value of a school.
Also, as you krindorr mentioned above, this is only a look at football programs and don't take into account basketball or overall sports programs so should be viewed in that light as well.
Football program success should not be as heavily weighted because it's often not entirely sustainable once a successful coach leaves for whatever reason. Nebraska and Boise St are good examples of schools that had much better success at one point than they're experiencing now. Alabama wasn't the powerhouse they are now prior to Saban either. Saban is now 71 yrs old. Utah may well be in that group very soon too.