The discussion for a while, until they play in the Orange Bowl is if they "deserve" to be here. It's a squishy word which you can use to whichever end you prefer. I'll leave you to decide that, but if you're looking for some insight into the discomfort of some people, it's this:
This is the first year in which the MAC had at least four teams ranked in the AP poll at any point in the season. The Week 9 poll had Ohio at No. 24, coming off a bye and still beaming as "the team that beat Penn State," a win which started to look excellent. Then they lost to Miami and fell off the table.
Two weeks later Toledo debuted at No. 25, aided by beating undefeated Cincinnati. They lost to Ball State, and that was that for them.
Two more weeks after that, Kent State slid into the picture at No. 23, disposing of undefeated Rutgers and capturing the hearts and minds of everybody.
And finally, after the end of the regular season, there stood Northern Illinois, shining brightly at No. 21. All they did was have their way with everybody in the MAC, but they didn't reach the BCS top 25 until last week.
That is what makes this so odd. NIU just may be the first at-large team to play in a BCS bowl despite not appearing the top 25 until after the regular season. To go from out of the picture to No. 15 in two short weeks means that everything just went their way in terms of other games.
Forget about how good NIU is or should be — that sudden ascension up the ladder could indicate what rankles some people. This season was supposed to be about Ohio; it wasn't. Then we latched on Big East headhunters Toledo or Kent State. For a week I thought it could've even been Bowling Green's year, because I am a stupid dreamer. And this comes from somebody who gobbles up as much MAC as possible: even I didn't pay enough attention to Northern Illinois during the regular season.
Additionally NIU didn't really beat up on anybody except their own men, unless you count Kansas. To get into the BCS as a non-AQ with a single loss is also a new milestone. And you know how people initially hate change.