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If Jim Harbaugh leaves for Michigan—still unlikely but entirely possible—it would be just about an unprecedented move. It's possible there'd be nothing like it ever done in NFL history.

In almost every instance, when a coach decides to leave the NFL for college, it's because he is chased out of the NFL. He's discarded. He's unwanted. There is a mob with pitchforks and torches in hot pursuit to the county line.

Jim Harbaugh coaching record Season Team W-L 2004 University of San Diego 7-4 2005 University of San Diego 11-1 2006 University of San Diego 11-1 2007 Stanford 4-8 2008 Stanford 5-7 2009 Stanford 8-5 2010 Stanford 12-1 2011 49ers 13-3 2012 49ers 11-4-1 2013 49ers 12-4 2014 49ers 7-7 sports-reference.com

We saw that with Louisville head coach Bobby Petrino. He was overmatched coming from college to coach the Atlanta Falcons and quit in the middle of the night, infamously leaving a note in the lockers of Falcons players. Players were apoplectic. Some called him a coward. He ran back to college so fast his speed qualified him for the Olympics. The NFL had eaten up another coach.

Nick Saban looks like a genius now, but when he was with the Miami Dolphins, he was awful. After first saying he wasn't leaving for college, then, you know, leaving for college, he was another coach chased out of the pros.

There's a big difference with Harbaugh. This wasn't a good season, but it's not hyperbole to say that he would be the No. 1 candidate for every potential NFL head coaching opening this offseason. He's not being chased out of the NFL. He's the prom king.

Pete Carroll had some good years with the Patriots before leaving for USC, but nothing like Harbaugh, who's made it to a Super Bowl, two conference title games and was named NFL Coach of the Year in 2011. The legendary Bill Walsh was close, going from the 49ers to Stanford. But there was a television stint in between, so Walsh didn't really directly leave for college the way Harbaugh potentially would. Jim Mora Jr. is another candidate but, again, nothing like Harbaugh.

The changing economics in college football could be a part of Harbaugh making history. He reportedly was offered $8 million a year, which would make him the highest paid coach in football, nearly a million dollars clear of Saban.

Journalists I trust say the reported offer to Harbaugh wasn't accurate. That's not surprising. What is clear, though, is Harbaugh's interest in the job.

I can say with certainty that Harbaugh's interest is piqued, where just several months ago the idea of going there didn't truly attract him, according to several NFL sources. The money—however much it is—changed things, sure, but I'm told there's another factor making Harbaugh consider Michigan.

Harbaugh, I'm told, has been dispirited by the off-field troubles in the 49ers locker room. That is, well, odd, since he was the coach of the team as they occurred. But I am told by several people close to him that Harbaugh blames some of those problems on the front office. I wasn't told Harbaugh's reasoning on this, but Harbaugh putting some of the blame on the front office isn't a stunner. The two entities are like Al Capone and Bugs Moran. Harbaugh probably blames the decline of the American middle class family on the 49ers front office.

But still, Harbaugh likely will stay, for the same reason no other highly successful coach has gone directly from the NFL to college by choice: ego.

Most pro coaches still see college football as beneath them. No coach would ever say this publicly, but once you've been in the NFL, it's hard to take a step back to the minor league. And that's how they see it. One current NFL head coach told me that "my ego wouldn't let me take a step backwards."

The resounding view of Harbaugh from team officials across the NFL is that he will end up coaching an NFL team where he has almost total control. I'm also not so sure the Raiders are Harbaugh's destination. One team I've been repeatedly told to put on Harbaugh Watch are the Falcons.

Again, it's doubtful, though not impossible, that Harbaugh leaves for Michigan. You can't rule it out until he officially tells them no.

But if Harbaugh does leave the pros for college, history will be made. We've never seen anything like that before in history—A guy, at the apex of his career, leaving for college. Unheard of.

Mike Freeman covers the NFL for Bleacher Report.