What does it take to get ranked in the FBS Football rankings if you are not in the SEC

Where do you think that a Power 5 team that is 3-1, is ranked 3rd for total defense and has the leading rusher in the nation is ranked if they are not in the SEC? THEY ARE NOT RANKED! Illinois is the 3rd best defense in the nation. That is just above Alabama and 9 above Georgia. Chase Brown is the rushing yards leader with 733 yards. The closest in the SEC is Raheim Sanders from Arkansas with 609. What is wrong with this?