Conclusion: Aggy is flailing and made an impulsive decision after losing to Ole Miss (or Tennessee).
How do we know this? There's only two possibilities: (1) it was planned before those losses or (2) it wasn't. Let's use the process of elimination to determine which of these possibilities is more likely.
If this had been planned out...
Jimbo probably should have been given a chance to talk to his team.
The search for a replacement should be much further along if not already done.
There would be basically nothing to gain from releasing the coach this late into the season.
Every penny of the buyout as well as the true cost of getting the new staff (consultants, interviews, onboarding, the contracts themselves) would have been budgeted
If this was not planned out...
Dumpster fire optics
No clear frontrunner.
Players hitting the portal early.
Weasel words in the presser about how the buyout will be paid and no details about the true cost of the decision.
I feel pretty safe in concluding that Aggy leadership made a rash decision here with suboptimal consequences to ensue.
Thinking Aloud: Why would Aggy make such an important decision impulsively rather than strategically?
I'll treat two related questions separately here: (1) Why fire Jimbo Fisher and (2) Why fire him now?
1. He hadn't been winning (duh) but from Aggy's perspective the decision to fire is more complicated than that. It is affected by the $76 million dollar elephant in the room and can't be made exclusively based on whether he's winning--you ALSO have to (A) reach a firm (and I mean VERY firm) belief that Jimbo is not going to turn things around and (B) convince yourself that the cost of delaying the inevitable is greater than the cost of the buyout. Part A is the "leash" most coaches at other programs get for at least two years, although when the expectations are so high that you're receiving national championship plaques based on the foregone conclusions of your future successes, it's fair to say that the leash would have been a bit shorter in Collie Station than anywhere else. Good thing for Jimbo there's that Part B, which had the perverse effect of greatly lengthening the leash.
Part B, again, is about the appraised value of the future success Aggy believes (in its mind) it would be missing out on because of Jimbo's performance compared to the knowable dollar amount it would cost to break up with Jimbo. You don't fire him unless this appraised value is pretty high. Even in a mediocre season, Aggy football probably makes a decent amount of money. So how much more would Aggy be making if their team had been CFP contenders, and how much more does Aggy believe (in its mind) it could make? Not much, and a whole lot, respectively.
Aggy therefore appraised its hypothetical future success an astronomical amount. When the case could be made, behind closed doors, that the only thing standing between Aggy and that hypothetical future success was Jimbo Fisher, it would not be a matter of if, but when and how, to fire him.
2. Why now? This gets back to Aggy's self-appraisal of the value of its hypothetical future success in the absence of Fisher. Like a married man convinced he would be drowning in a sea of post-separation pussy, Aggy reasoned to itself that the quicker the bandage is ripped the quicker they could transition to those hypothetical future successes. But...
...that doesn't quite answer the question of why now because it leaves unanswered the question of why not before? After all, all the same factors were in place last season. His trajectory was near or worse than Sumlin's, and you don't pay top dollar to get the exact same results. What could it be, then?
I wonder, what is different about 2023 that makes the prospect of another year of Jimbo Fisher absolutely intolerable? Did they really think, in 2022, that Jimbo's team would turn a corner this season? I suppose anything is possible. So rather than draw any firm conclusions I'll simply speculate.
An Educated Guess: Jimbo Fisher already would have been a dead man walking into the 2024 season; the looming possibility of an embarrassing narrative (Jimbo's firing caused by a loss to Texas) so terrified Aggy that they were spooked into an impulsive decision intended to pre-emptively squash that possibility, consequences (and budget) be damned.
TLDR: $100M paid for a built-in excuse for losing to us in 2024.