Look at the following chart. And when you do, pay close attention to the first four names.
|Gary Pinkel||Missouri Tigers||15th season|
|Mark Richt||Georgia Bulldogs||15th season|
|Les Miles||LSU Tigers||11th season|
|Steve Spurrier||South Carolina Gamecocks||11th season|
|Nick Saban||Alabama Crimson Tide||9th season|
|Dan Mullen||Mississippi St. Bulldogs||7th season|
|Hugh Freeze||Ole Miss Rebels||4th season|
|Kevin Sumlin||Texas A&M Aggies||4th season|
|Bret Bielema||Arkansas Razorbacks||3rd season|
|Butch Jones||Tennessee Volunteers||3rd season|
|Gus Malzahn||Auburn Tigers||3rd season|
|Mark Stoops||Kentucky Wildcats||3rd season|
|Derek Mason||Vanderbilt Commodores||2nd season|
|Jim McElwain||Florida Gators||1st season|
The first name on the list -- Gary Pinkel -- is retiring for health reasons at the end of the year. The second name, Mark Richt, has been the subject of hot seat rumors practically since the term "hot seat" was invented. The third, Les Miles, is already rumored to be coaching for his job, if he hasn't already coached himself out of it. And the fourth, Steve Spurrier, resigned midseason.
There's been a lot of focus on those men and their future plans, but not a lot of discussion of what their departures mean when you put them all together. Between those four names, the SEC could lose as much as 52 years of head-coaching tenure in a single season. I think it's unlikely to lose quite that much; my sense is still that Mark Richt will survive for another year unless his team gets annihilated against Georgia Tech this week. Still, the combined departures of Pinkel, Miles and Spurrier would take away 37 years of coaching merely at their current schools, setting aside the fact that all three oversaw other programs before taking over their present (or, in Spurrier's case, most recent) teams.
And if all four leave, Nick Saban will become the dean of SEC coaches. (Despite the rumors that he would coach in the NFL or for the Texas Longhorns or wherever.) The second longest-tenured coach in the conference, assuming he doesn't take a job elsewhere and add to the brain drain, would be Dan Mullen -- who was himself fending off hot-seat rumors a couple of years ago. No other coach would have more than five years in their current job.
Here's another way to put the potential losses into perspective: If you combine the tenures of the most recent ex-head coaches of the 10 other schools in the SEC, you come out with 36 years. (And that's counting Mike Sherman, who never coached a single game in the SEC, and Bret Bielema as replacing Bobby Petrino instead of John L. Smith.) If just Pinkel, Spurrier and Miles end up leaving, it will still be one of the biggest upheavals in coaching ranks in the conference in a long time.
Part of that is simple logic. If a coach doesn't do well in the SEC or most other conferences, he's going to be out of a job sooner rather than later. And if a coach does well, the only things that generally cause him to leave are retirement or taking a better job. (Or riding a motorcycle after making poor life choices, but let's set that example aside for the moment.)
After a decade, though, even the most accomplished regimes start to feel a little stale. Some of them, like Spurrier at South Carolina, outright collapse. In other cases, like Miles at LSU, things that were once adorable quirks start to grate on fan bases who understandably aren't as quick to defend unique game-management philosophies when the winning slows down a bit, or stalls out. Pinkel's retirement is a different animal, given that he's still well-liked in Missouri and probably would have gotten to 2016 without his health issues, but the Tigers head coach has also outrun hot seat rumors a time or two. If Nick Saban were to go through back-to-back seasons of eight or nine wins, there would probably be some grumbling in Tuscaloosa.
Even if you take all that into account, though, to have at least three of those coaches facing the end of their career in a season is remarkable, and not in a good way. All three departures were inevitable; every head coach eventually steps aside or gets fired. It wasn't inevitable that Spurrier, Pinkel, Miles and perhaps Richt all leave at the same time, though. And just three of those losses would make the SEC a very different place in 2016.