The most enigmatic potential head-coaching candidate is one that is currently still employed.
And many of them appear to be waiting on the future of Houston coach Bill O'Brien, according to several sources.
The third-year Texans coach has won the AFC South two years in a row -- with a revolving door at quarterback -- and is searching for his first playoff win today. But there is a real chance, based on several factors, that he will be coaching another team next year.
If that happens, O'Brien may soar to the top of the list.
A coach trade is possible. As is a mutual parting of the ways. As is the Texans simply deciding three years is enough; time to go in a different direction.
A win would at least prolong the wait or push the topic of his future to 2017, depending on who you ask.
Perhaps just as important is that teams with vacancies believe O'Brien could be available. With a talent pool full of intriguing candidates but without a lot of star power, O'Brien would immediately become among the most coveted.
As for the reasons why the Texans might be looking for a new coach, the fit between O'Brien, GM Rick Smith, and owner Bob McNair has always been an odd one. Personalities have clashes, as have approaches to building a football team.
The signing of $72-million quarterback Brock Osweiler, who struggled mightily and was eventually benched by O'Brien, has served as a lightning rod for argument and frustration. Whether he was forced on O'Brien by McNair and the team's brass, as most sources believe, or whether Osweiler is merely a symbol of a brutal free-agent miss, his struggles loom large.