The coaching star of HBO’s "Hard Knocks" this season was supposed to be Detroit Lions head man Dan Campbell, he of both the equally oversized frame and personality. The gravelly voice. The unpredictable twists in his speeches. The willingness to do up-downs with the players.

The guy is, unquestionably, a unique force of personality that producers must have hoped would somehow make a three-win team for a franchise with one playoff victory in 65 seasons worth watching.

And Campbell has delivered his part as Must-See TV.

Yet the coaching figures who are producing the most compelling storylines come from Campbell’s staff of assistants.

Namely Aaron Glenn, Duce Staley and Kelvin Sheppard, each of whom, like Campbell, is a former NFL player. They are also, unlike Campbell, African Americans.

And that, for the league, has to be welcome news.

The Lions may have the most diverse coaching staff in a league that is so desperate for diversity that it has numerous rules, clumsy protocols and even draft-pick incentivized reward programs to encourage the hiring of coaches and front-office personnel who reflect the racial make-up of the players.

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Whether every fan cares about this isn’t the issue. The NFL does, incredibly so. It’s important to the league. The goal is to make it so job candidates are seen for the caliber of their ability, experience and potential and not ignored because they don’t fit the historic vision of head coach.

Despite decades of trying, the NFL still struggles with it. And even those who prefer the best person gets the job and couldn’t care less what their favorite team's staff looks like as long as it delivers victories would have to acknowledge that the current system has done a chronically poor job of identifying highly qualified non-white coaches.

Well, publicity often leads to promotion and "Hard Knocks" is making a coaching name — and a potential career boost — for some Lions staffers.

Detroit has 22 assistant coaches for the offense, defense and special teams. Eleven of them are African Americans. The front office is led by general manager Brad Holmes, who is also African American, and has unearthed some excellent late-round draft picks.

Campbell has put a premium on hiring former players as coaches, and in a league where the majority of the rosters are made up of African Americans, this is the natural result. Or should be.

It includes Glenn, 50, who spent 15 seasons in the league, most notably as a Pro Bowl defensive back with the New York Jets, serving as defensive coordinator.

There is Staley, 47, a 10-year vet as a bruising rusher, who is the Lions' assistant head coach and handles the running backs.

Meanwhile, Sheppard, 34, spent eight seasons as a linebacker bouncing around the league and got into coaching only last year, when Campbell plucked him off the support staff at LSU.

Glenn has come across as passionate (to say the least), organized and clearly not just respected but beloved by his players. He commands attention through his professionalism and charisma.

The proof of his ability to become a head coach will be determined by how his defense performs this season, as it should. But it’s impossible to watch him work behind the scenes and not see someone who projects as more than capable of running his own team.

Staley is no different. One recurring storyline has been Staley trying to coach D'Andre Swift not just how to run, but to have the mentality needed to run inside and maximize his abilities. It’s a rare unfettered look at pure coaching, ups and downs alike, both mental and strategic. If Swift shines this season, Staley’s coaching talents will be clear.

Then there is the excellent play of rookie linebacker Malcolm Rodriguez, who was drafted in the sixth round. It features Sheppard teaching and encouraging Rodriguez, and a blunt and powerful speech by Sheppard challenging his veterans to match the rookie's intensity and warning them that one of them is about to lose their starting spot.

There are more examples, of course, including work by assistants such as Mark Brunell and Hank Fraley, who are white. Race isn’t a focus on the show. Which is great.

In a perfect world, none of this should matter or should stand out. In a perfect world, this isn’t even discussed.

NFL coaches should be great coaches, of course. This is dog-bites-man type stuff. Yet "Hard Knocks" is presenting impressive moments to decision-makers in the league, most notably ownership or those with the ear of ownership. And it is coming in a far more organic — and thus preferable — manner than all the forced sham interviews or mid-round draft pick rewards.

Anyone watching "Hard Knocks" should be able to envision Glenn or Staley as a head coach, or Sheppard and others as moving up the ranks. Again, appearances aren’t performances, but this is how the world works. Looking the part matters, even if it shouldn’t. NFL hiring has long proven that.

For a league that has tried almost everything, maybe something new is coming from something old; "Hard Knocks" has been around since 2001.

Now the Lions just need to actually win, of course.