CINCINNATI -- Ask people for the day when the once-so-promising Marvin Lewis’ Bengals took a downward turn that couldn’t be reversed, and you’ll likely get the ghoulish and wickedly disappointing playoff collapse vs. Pittsburgh in January 2016.

But I see that day as the one when their already serious condition became terminal. They’ve not had one truly good outing since. They’ve gone rapidly toward the tank, and they’ve been on a respirator the last two games, suffering losses that will live among the most embarrassing in franchise history. The 15-year Lewis Era is dead -- surely by mutual agreement between the coach and the Brown family -- even if Lewis coaches the remaining two games and continues to deny credible reports, he has already decided not to seek a renewal of his contract for 2018.

ESPN: Marvin Lewis to leave after this season

The first sign of a fatal condition – the one you recognize only in hindsight – is 20-20 now for me. It was six years before the Pittsburgh debacle. It was the first-round playoff on Jan. 9, 2010 against the New York Jets. (That’s the 2009 season, of course.)

The Bengals were AFC North champions for the second time under Lewis, clearly on course as the club Lewis had rescued from the pits since arriving in 2003. The Jets were a 9-7 Wild Card team that had reached the playoffs via tiebreaker. The Bengals had Carson Palmer in the young prime of his career, while the Jets were quarterbacked by Mark Sanchez, ranked a journeyman both then and in posterity. The Bengals were proudly defending their home turf at Paul Brown Stadium. Their 41st straight sellout crowd was pumped, ready to cast away the demons from nineteen straight years without a playoff win and the 2005 season playoff game with the instant sucker-punch of a second-play Palmer knee injury.

One playoff victory – one totally achievable and expected playoff victory – might have prevented what we’re experiencing now, but New York won 24-14 and it wasn’t even interesting. The Jets shrugged off an early 7-0 deficit to lead 21-7 after three quarters. The Bengals finished with a sickly 110 net passing yards and kicker Shayne Graham crippled any nascent comeback hopes with FG chokes from 35 and 28 yards.

Then, in my 17th season as Bengals public relations director, I had never been so confident the Bengals would win a key game, and it just seemed so queasily wrong for some time. Heading into the 2010 season, I thought often about how much better the atmosphere around the team would have been with just that one damn playoff home victory over the not-so-great Jets.

But then came a 4-12 disaster season in 2010, as the toxic Terrell Owens and the tired antics of Chad Johnson contributed to the biggest fan turn-off in franchise history. Season ticket sales took an historic dip as Palmer extended the disaster by refusing to play in 2011. Even as Lewis performed a remarkable turnaround over 2011-15 (making the playoffs five straight times) the fan base remained depleted. Bengals swagger was hard to develop as the club had to virtually beg fans for ticket sales to avoid the ignominy of home TV blackouts.

And still Lewis could not win a playoff game. For the ’11 season, there was the mostly excused 31-10 loss for rookie QB Andy Dalton at Houston. In 2012, another loss at Houston featured Dalton puzzlingly no better than the year before. For ’13, a gut bomb much like that ’09 Jets game, as the division champs went down 27-10 at home against a totally pedestrian Chargers outfit. The 2014 season saw an injury depleted team that put up no resistance (26-10) at Indianapolis, and ’15 brought that Pittsburgh game you already know far too well.

Why couldn’t Lewis get over the hump, after lifting the Bengals so far from the 2-14 laughingstocks of 2002 and the .295 winning percentage of the previous 11 seasons?

It’s difficult for me to take that on as a media critic. I worked daily with Lewis for 14 years, and I admire him not only for his franchise-records of 123 wins and seven playoff trips, but for being the most gracious and courteous individual imaginable to all Bengals employees, despite the immense pressures that turn so many head coaches into something much less.

But regarding what never came to be at playoff crunch time, I will question the coach for coddling too many players whose talent was enticing but whose poor behavior, in my opinion, went unchecked and eroded team chemistry. Think Corey Dillon, the aforementioned Johnson and Owens, Jermaine Gresham, Adam Jones and Vontaze Burfict. I’d even throw in Geno Atkins, whose implacable resistance to media responsibilities has been completely tolerated, which sets a bad example.

Though I’ve never spent daily time in a Bill Belichick or Mike Tomlin locker room, I have to believe the focus on winning in those places must be somehow very different.

Marvin is both the best coach and the most keenly disappointing coach in Bengals history. He lifted the franchise to a place where the Lombardi Trophy replaced “having a good season” as the team’s stated (and plausible) goal. But he lost more playoff games without a win than any coach in NFL history, and the pressures of that have combined with many other factors to crush the team in 2017.

If he wishes, Marvin will go to another team in some capacity in 2018. He may even hoist a Lombardi someday. And the Bengals will move on for their 51st season, a better outfit for having had Lewis on board.

Jack Brennan was Bengals public relations director from 1994-2016, following nine seasons as Bengals beat writer for the Cincinnati Post (1984-89) and Cincinnati Enquirer (1991-93). This column represents his opinion.