BY NEIL HAYES
For the Sun-Times

Only two people know the answer to a mystery almost 20 years in the making. One is former Raiders owner Al Davis, who died in 2011. The other is John Fox, the former Panthers and Broncos coach who was hired to the same job Friday by the Bears.

And he never has addressed the subject publicly.

It is unheard-of for a coordinator to walk away from a team close to the start of the regular season, but that’s what Fox did when he resigned as the Raiders’ defensive coordinator between the fourth and fifth exhibition games in 1996. Fox’s decision left players, coaches and the media stunned and forced then-Raiders coach Mike White to scramble to find a last-second replacement.

‘‘It’s a bombshell,’’ former Raiders defensive lineman Nolan Harrison said at the time. ‘‘It’s hard to lose someone from the coaching staff you actually like.’’

White claimed Fox resigned for personal reasons. The Raiders issued a statement that quoted Fox as saying he resigned for ‘‘reasons he would rather not discuss.’’ It was a stunning decision many considered career suicide.

If you thought the 2014 Bears were rife with dysfunction, you should’ve seen the Raiders in the mid-1990s. Strange seasons, such as the one the Bears endured in 2014, were the norm for them.

Davis’ bizarre leadership created paranoia so profound that White refused to identify the person responsible for calling offensive plays. He insisted plays were called by committee, with himself, offensive coordinator Jim Fassel and offensive line coach Joe Bugel all offering input before a call was made prior to the play clock expiring.

Yeah, right. I was a beat reporter covering the team that season. By midseason, I would ask Fassel to comment about the weather because it was the only subject he could discuss without fear of repercussion. His daily weather updates became a running joke.

Davis’ meddling affected the entire organization. The Raiders’ 8-2 start in 1995 was largely a product of an effective short-passing game, but Davis loved to throw deep and insisted on changes before a critical game against a Cowboys team that would go on to be crowned Super Bowl champions.

Quarterback Jeff Hostetler threw 11 deep balls that day, many into the teeth of a Cowboys secondary that featured Deion Sanders, before getting sacked and injured. The Raiders lost their last six games, and Fox came close to losing his job.

It was no secret Fox and Davis had philosophical differences heading into the Raiders’ fourth exhibition game in 1996 in Atlanta. Then-Falcons quarterback Jeff George had missed most of training camp in a contract dispute and had practiced only once before shredding Fox’s defense by completing 17 of 24 passes for 233 yards.

One potential explanation for why Fox fled seems reasonable enough. Davis accosted him on the plane trip home or after they returned to training camp and demanded changes. Fox refused and left.

Fox moved his family to St. Louis and worked as a personnel consultant for the Rams. Even years after the fact, he refused to address specifics regarding his mysterious departure.

‘‘I didn’t see that working out,’’ Fox said before Super Bowl XXXV in 2001, when he was the Giants’ defensive coordinator under Fassel. ‘‘Al owns the team, and when you don’t see eye-to-eye with the owner, it’s time to move on.’’

Either way, it’s likely Fox would have been fired with White and other staff members after the Raiders finished 7-9 in 1996.

That offseason, former Giants general manager Ernie Accorsi hired Fassel as coach. Fassel promptly named Fox to be his defensive coordinator, a position he would hold until he was named coach of the Panthers in 2002.

It was with the Giants that Fox became friends with current Saints coach Sean Payton, who likely played a role in Fox landing in Chicago because of his close relationship with recently hired Bears general manager Ryan Pace, a longtime Saints employee.

‘‘A lot of times in this league, things don’t work out and people move on,’’ Fox said about his departure from the Raiders. ‘‘It doesn’t mean there’s anything wrong with the organization or the coach. Coaches change addresses in this league.’’

Contact Neil Hayes at nhayes40@gmail.com or at neilhayeswriter.com.