If the entire point is to derive a correlation between disappointment and let-down losses, then excluding entire classes of disappointed teams only serves to weaken the hypothesis, and any conclusion that might be drawn from it.
That's fair. But there's a degree to which that's hard. If you're trying to figure out "disappointment", you have to realize that there are different kinds of disappointment.
I'd wager that Ohio State 2017 or 2018 disappointment is a lot different than Michigan 2018 or Georgia 2018 disappointment. In both cases OSU was the conference champion in a strong P5 conference and was excluded. But in neither case was that disappointment all that much of a surprise to them. They knew going into the CCG that winning the game was in their control, but that the CFP was out of their hands.
Conversely, Michigan and Georgia were both in a position where a win would pretty much undoubtedly put them in [although for Michigan they'd have needed to beat NU too], and a loss excluded them. Basically the outcome WAS within their control, and their own inability to prevail destroyed their shot at it. And again, unlike OSU, both teams also didn't hit their secondary goal of a conference championship. UM by not making it to the CCG, and UGA by losing the CCG.
Again I'll go to the 2008 Texas example because it's an important one. That Texas team didn't lose a final game, it lost a tie-breaker without having any control at all. And they watched their hated archrival-- that they'd already beaten in the regular season by double digits on a neutral field-- take away every single one of their postseason goals, effectively at the flip of a coin. That was an unbelievably bitter outcome for that team. I don't think this year's Georgia or Michigan could have been ANY more bitterly disappointed than that 2008 Texas team was.
Again, there's a question of motivation. I don't think that Texas team was necessarily "disappointed", I think it's far more likely they were f'ing angry
. It's the very fact that they believed they were every bit as qualified--probably more so due to H2H
--as Oklahoma. They wanted to prove a point. It's a different feeling to be excluded because you didn't measure up on the field, rather than believing that you never got your shot and the team that got their shot should have been you
Do you honestly think that Michigan or Georgia this year had that sort of fire? That they wanted to prove that they were legitimate CFP contenders, and that they were unfairly excluded? Did Michigan have any argument that they should have been in over ND or over OSU [who didn't even get in]? Did Georgia have any argument they should have been in over Alabama?
No, Michigan and Georgia were excluded because they lost. Texas was excluded because a team they beat by double digits won an irrelevant beauty contest.