Eyebrows went up across the country back in September when Appalachian State, a member of what used to be called Division I-AA, stunned nationally-ranked Michigan in its season opener.

It’s not the only upset this season by a team from what is now called the Football Championship Subdivision over a school from Division I-A — now labeled the Football Bowl Subdivision.

Several other of the “lower-rated” teams have posted wins: Southern Illinois over Mid-American member Northern Illinois; New Hampshire over Conference USA’s Marshall; McNeese State over Louisiana-Lafayette of the Sun Belt; North Dakota State over the Big Ten’s Minnesota; and this this past weekend, Delaware over independent Navy.

There’s still the possibility of a few more of these so-called upsets before season’s end.

Maybe it’s no surprise that a full 57 percent of the Bowl Subdivision teams are playing at least one game against their little brothers from the Championship Subdivision. A few — Mississippi, Hawaii and New Mexico State — have a pair of games against the old I-AA's.

Why?

There are probably several reasons:

One, obviously, is to play a cupcake to get an easy victory.

Another aim is to get a lot of players into an early game in order to see who performs against someone other than themselves. Good depth can come from this.

A third likely reason is to have a middle-season game against an opponent that should be easy pickin’s. With a rough schedule, having a date like that could be better than an open date since it continues the season but without too much of a burden.

Among other reasons could be that it’s hard to find games against Division I-A teams. East Carolina fans can easily remember when other I-A’s didn’t want to play ECU and the school had to schedule teams from the lower ranks. The addition of a 12th game has added to that problem.

There may also be some politics involved, including situations in which a state institution plays against another state school. But who knows?

Then, there’s always the cash reason. Usually, a Division I-A can bring in a I-AA, draw a good home crowd, get a lopsided victory, and send the visitor home with a decent paycheck and little else.

Some conferences dig deep into Division I-AA — I’m going to use that term because it’s easier to use and understand than the new terminology — while others seem to avoid them.

The fabled Pac-10 has the “best” record of not playing the small schools. Of its 10 members, only one, Arizona, has a game against a I-AA team, giving that league a "percentage" of 10.

The next two leagues will probably surprise you. Second best, with just two of its eight teams dipping into 1-AA (25 percent) is the Sun Belt. Only Louisiana-Monroe and Louisiana-Lafayette, have such games. Then comes the Mountain West with four of its nine (44.4 percent) playing down: Air Force, Colorado State, New Mexico and San Diego State.

Worst among the leagues is the Western Athletic. Eight of its nine schools play games against I-AAs, and two of them — Hawaii and New Mexico State — each play two Division I-AA teams.

Now that’s a really strong schedule!

Ranking in the middle, from low to high, come the Atlantic Coast with six of 12 (50 percent); Mid-American, with seven of its 13 playing down (53.8 percent); the Southeastern with seven of 12 (58.3 percent); the Big 12 with eight of 12 (75 percent); the Big East with six of eight (75 percent); and the Big Ten with eight of 11 (77.7 percent).

Eight of 12 schools (66.7 percent) from East Carolina’s league, Conference USA, play I-AA foes.

There are three independent teams, Notre Dame, Army and Navy, and both of the latter play one game down.

The percentage for the indies actually could be higher, considering that Western Kentucky is in its transition season, moving from I-AA to I-A. I did not figure in its percentages, since it largely is still playing a I-AA schedule.

It’s worth noting that in this week’s BCS Top 25, over half (13) played at least one game against a Division I-AA — top-ranked Ohio State; No. 2 Boston College; No. 8 Kansas; No. 9 Missouri; No. 10 Georgia; No. 12 Michigan; No. 13 Connecticut; Now. 14 Hawaii (two games); No. 17 Alabama; No. 18 South Florida; No. 21 Wisconsin; No. 22 Boise State and No. 25 Clemson.

Maybe the old saying that for years "explained" why the lesser known schools didn't get a fair shake in the polls still has a modicum of truth: It ain’t who you play, it’s who you are.