Mike Zimmer’s been a fan favorite for NFL head coaching jobs over the last couple of seasons, but teams have consistently been turned off by his straightforward attitude and bluntness. Perhaps they’re not fully aware of what he can do to their defense.

Since 2008, Zimmer has coordinated the defensive unit in Cincinnati. Prior to his current job, he spent seven years as Dallas’ defensive coordinator from 2000 to 2006, and another year under Bobby Petrino in 2007 with the Atlanta Falcons.

He’s a defensive-minded, no-nonsense coach that’s done well enough to have been interviewed for multiple head coaching jobs in the past. And now, after the Bengals had yet another solid season on the defensive side of the ball, there’s an even bigger chance he leaves the ‘Nati this year.

And Cincinnati can’t afford that.

Mike Zimmer’s Pre-Cincinnati Impact

Rather than just looking at Cincinnati, I decided to glance all the way back to Zimmer’s Dallas days. How did his defenses perform throughout his defensive coordinating career? Were they top units?

Naturally, the metric analyzed was numberFire’s Adjusted Defensive Net Expected Points. What Adj. DNEP looks at is how many points, above or below expectation, a particular defense had surrendered or prevented over the course of the season. This, then, is adjusted for strength of schedule.

Prior to joining the Bengals in 2008, Zimmer’s 2000-2007 coordinating left him with the following defensive ranks:

Really, regardless of personnel, his final defensive rankings were nothing to raise eyebrows prior to going to Cincinnati. The best defense he had coached was in 2005, which, interestingly enough, was a year where the Cowboys forced Zimmer to run a 3-4 scheme – something he had never done. Rookie DeMarcus Ware certainly made the transition easier for Zimmer, however.

Overall, the metrics wouldn’t suggest that Zimmer, a defensive coach with more of a background in the secondary, was anything overly special from 2000-2007. But that all changed when he went to Cincinnati.

Zimmer in Cincinnati

Using the same metric as the one above, I compiled Zimmer’s defensive rankings from 2008 through 2013 while in Cincinnati. In addition to this, I added the Adjusted DPNEP and Adjusted DRNEP to reflect his pass and rush defense ranks.

Below is a chart depicting how his defenses have finished through the years, including how the Bengals defense performed during the two years prior to Zimmer’s start.

The growth of this defense can’t go unnoticed. When Zimmer took over, the Bengals had the 25th- and 23rd-worst defense in the NFL (2006 and 2007), and in the following year, Zimmer bumped that to the number 14 defensive unit in the league. Though he hit a bump in the road in 2010 (didn’t the entire Bengals team though?), Zimmer has since bounced back to have a top-10 unit in each of his last three seasons, including the second-best one in 2013.

Since when do the Cincinnati Bengals play defense?

What’s most impressive about Zimmer’s 2013 coaching campaign is that he did this all while losing versatile cornerback Leon Hall, and All-Pro defensive tackle Geno Atkins. Not only that, he put it together with a group of linebackers that were rarely high draft picks. It was scheme and coaching on the defensive side that got the Bengals the AFC North title this season.

It’s no coincidence that Cincinnati’s seen three straight playoff trips with a top-10 defensive unit. Mike Zimmer has changed the identity of this franchise.

Where Should He Go?

Let’s, just for a second, assume Zimmer interviews great and is wanted by every team with a head coaching vacancy. Is there a particular squad that he would fit well with?

I’ve been a huge proponent of Zimmer going to Detroit. The secondary, while depleted, struggled this season, and in a division with the Bears' and Packers' passing attack, a defensive backs-oriented coach would make a lot of sense. And imagining what he could do with the talent on Detroit's defensive line should make any Lions’ fan excited about the possibility.

Moreover, Zimmer’s hard-nosed attitude has made headache players Vontaze Burfict and Adam "Pacman" Jones into more-than-solid pieces on the Bengals defense. Perhaps this could translate to a team, Detroit, that’s consistently been mentally unstable.

Cincinnati will be fortunate if Zimmer stays put. He’s changed the way football fans view what used to be the laughingstock of the NFL, and made them into a perennial contender. But perhaps this is the year teams realize what he can do for an NFL team and franchise, giving him a chance as a head coach in the league.