FRISCO (105.3 THE FAN) –  The most publicized reason for the departure from the Dallas Cowboys of Matt Eberflus — in theory this franchise’s defensive coordinator-in-waiting — concerns the “toes’’ of his immediate supervisor and mentor, Rod Marinelli.

But in truth, that’s isn’t just the most publicized reason Eberflus is leaving; it’s also, and only, the most polite reason Eberflus is leaving.

It is accurate to report, as ESPN has, that Dallas was willing to be creative on its staff in order to retain the highly-regarded Eberflus, who has served as the Cowboys linebackers coach since 2011 and who last year, in another tip to his skills, was named defensive “passing game coordinator.’’ How about bumping Marinelli up to “assistant head coach,’’ anticipating a future retirement from the 68-year-old, with Eberflus then holding the title of defensive coordinator?

Eberflus’ unwillingness to accept that promotion certainly is in part about not wanting to take Marinelli’s job away from him. So we can put that somewhere about the Top 7 Reasons Eberflus is Leaving. The reasons, in chronological order:

1 Last January, Eberflus requested permission to interview with the 49ers for their defensive coordinator job. Dallas denied permission. That surely ruffled some feathers.

2 Shortly thereafter, the Cowboys offered Eberflus an extension, a handsome reward for his contributions to a 13-3 season. Fellow top staffers like Marinelli, offensive coordinator Scott Linehan and special-teams coordinator Rich Bisaccia accepted the extension.

Eberflus declined — a move that, as I’ve written before, “was a bet on himself and his future.’’

3 The 2017 Cowboys defense performed at a high level. Consider the work of Sean Lee, the development of Jaylon Smith, and the quick maturation of all the kids in the secondary. Eberflus was a big part of that; the “bet on himself’’ was working.

4 At some point, Eberflus forged a connection with Patriots offensive coordinator Josh McDaniels. I wrote at the start of the month that where McDaniels went (as a head coach), ‘Flus would follow. That’s all happening now, I’m told, with the Colts.

5 Rod’s “toes.’’ Yes. Among the top seven reasons.

6 If Eberflus is the Dallas defensive coordinator, but his “boss’’ (Marinelli) is the former defensive coordinator who is still his boss … what is Rod really in charge of? What is Matt really in charge of?

Most sailors want to captain their own ship. If Matt’s boss is Rod, it’s not really Matt’s ship.

7 And speaking of ships …Why remain anchored to a possibly sinking one?

I’m not predicting doom-and-gloom for head coach Jason Garrett’s Cowboys. But this is an 8-8 league, and if Dallas is mediocre again next season, in the penultimate year on Garrett’s contract? That will be the hottest of seats for RedBall, and for his staff.

Meanwhile, the Colts are starting over, coming off a 4-12 season. If Indy is 8-8 next year, the locals will be delighted with the improvement from the McDaniels/Eberflus staff. Eberflus will likely get the opportunity to fulfill the entirety of, say, a four-year contract, meaning that in terms of responsibility and in terms of patience, the Colts will be giving him a far longer leash that he can be promised in Dallas.

Seven reasons. Not just one.

Some of the reasons “impolite.’’ Not just “niceties.’’