12 games is a relatively short season, especially when the first three games or so are against crappy teams. Poll inertia is real, and somewhat necessary, to get a bigger sample size of the teams.

Right now, the SEC has five teams in:
Texas (#3, preseason #4)
Alabama (#7, preseason #5)
Ole Miss (#9, preseason #6)
Georgia (#10, preseason #1)
Tennessee (#11, preseason #15)

The B1G has 4:
Oregon (#1, #3)
Ohio State (#2, #2)
Penn State (#4, #8)
Indiana (#5, UR)

With the exception of Indiana, every one of these teams was expected to be in contention. Then they came in and took care of business.

Here is the ACC and Big 12’s problem: The teams that were supposed to be good all sucked and the teams that were supposed to suck were good.

ACC preseason expectations:
Florida State (UR, #10)
Clemson (#17, #14)
NC State (UR, #24)

The only exception here is Miami (#19, #8).

Actual ACC contenders:
SMU (#13, UR)
Miami (#8, #19)

Had Florida State, Clemson, and NC State actually been good, they would all be up in the playoffs pushing the SEC teams with multiple losses down.

Big 12 Preseason Expectations:
Utah (UR, #12)
Oklahoma State (UR, #17)
Kansas State (UR, #18)
Arizona (UR, #21)
Kansas (UR, #22)

There are no exceptions here. Of this group, Kansas State went 7-3. The rest went sub .500.

Then, the Big 12 Contenders:
BYU (#14, UR)
Colorado (#16, UR)
Arizona State (#21, UR)

BYU went 5-7 last year. Colorado went 4-8 last year. Arizona State went 3-9. It’s pretty obvious why the committee is skeptical of these teams.

But if the Big 12 teams that were expected to be good had actually lived up to expectations, we’d definitely have more teams in the playoffs.