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Everything came together for the UFC in 2016.

A year that may best be remembered in the mainstream for political unrest and sudden celebrity deaths was astonishingly sunny for the world's largest MMA promoter.

According to estimates by MMA Fighting's Dave Meltzer, five UFC pay-per-views cracked the 1 million buys threshold in 2016—which makes seven total for the company since November 2015, per Meltzer in the Wrestling Observer Newsletter (h/t MMA Payout). Boosted by Conor McGregor's evolution into a PPV dynamo and a headfirst dive into entertainment-based matchmaking, 2016 was likely the most financially successful year in UFC history.

And that's to say nothing of the $4 billion price tag on WME-IMG's purchase of the organization from Frank and Lorenzo Fertitta in July.

The fact the UFC was able to end an already stellar year with Ronda Rousey's long-awaited return to the cage on December 30 was just gravy. Like slamming an exclamation point at the end of a triumphant (and lucrative) sentence.

So now what?

Not to be a downer, but the credits didn't roll on New Year's Eve. Considering the enormous sum WME-IMG paid for the UFC and the lofty profit goals it reportedly has to hit to make the deal reach full value, the show must not only go on, but grow even bigger.

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In the short term, that could be a problem. The start of 2017 appears to have the UFC poised for a slump. At the least, there's a lot of uncertainty ahead.

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For starters, the talent pool looks unexpectedly shallow through the first half of the year. The UFC fired a lot of promotional bullets during 2016. Now, the fight company will have to try to reload while many of its proven PPV draws are unavailable for one reason or another.

McGregor has put himself on extended paternity leave and isn't expected back until summertime at the earliest. He's also making noise about a potentially contentious contract negotiation with the UFC before he returns. In addition to that—or perhaps as evidence of it—these pesky, pie-in-the-sky rumors about a boxing match with Floyd Mayweather Jr. refuse to die.

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Rousey may never fight again. Her comeback bout at UFC 207 lasted all of 48 seconds before she fell by TKO to Amanda Nunes. In the wake of it, questions about her training, her mindset and whether she'll bail on MMA altogether to try to make it as an actress are more pointed than ever.

Jon Jones is suspended until July. Even when he returns, UFC brass has voiced concerns about his future role with the company.

Brock Lesnar is also suspended, and his guest-starring appearance at July's UFC 200 ended in a failed drug test, controversy and now a lawsuit. Likewise, the UFC's experiment of bringing CM Punk into the fold to pop PPV buy rates blew up when Punk got undressed by Mickey Gall at UFC 203.

Georges St-Pierre remains in semiretirement and at odds with the organization on a new deal. St-Pierre was among a group of MMA athletes who announced the formation of a new labor association at a press conference in November. As a client of one of WME-IMG's biggest competitors, it remains to be seen if he and the UFC can come together.

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Nick Diaz is fresh off suspension, but he has nothing booked. Nate Diaz is likewise not on the docket and says he won't even entertain offers for anything less than a small fortune.

It's the perfect talent storm for the UFC, and it has created a noticeable power outage at the top of upcoming fight cards.

The end result is a 2017 schedule that so far resembles a gaping crater, potentially as wide as it is deep and dark.

As of this writing, there are just nine events scheduled between now and mid-April. That slate includes three PPVs (UFCs 208, 209 and 210) and so far just three title fights during the first 100 days of the year.

To put this toned-down run of play in perspective, the UFC put on 41 events each year during 2015 and 2016. During 2014, it did 46. If the current pace holds up, 2017 would be at speed for something more like 27 to 30.

Fewer events won't be a surprise and might turn out to be a good thing. During recent years, the UFC's schedule has reached the point of oversaturation with an ever-ballooning number of fights:

Most observers expect WME-IMG to begin hacking into the UFC's overstuffed live schedule and bring that number down sharply in the coming years.

At present, however, the events the UFC does have scheduled don't look like promotional dynamos.

On January 28, for example, the company will try to main-event a network TV broadcast on Fox—in theory, one of its higher-profile fight cards during this stretch—with a women's bantamweight contender bout between Valentina Shevchenko and Julianna Pena.

Both Shevchenko and Pena are fine fighters, but they are also virtual unknowns. Unless UFC on Fox 23 has a significant surprise in store, it's not going to score a high Nielsen rating.

A week after that on February 4, the UFC will use Dennis Bermudez vs. Chan Sung Jung as the featured attraction of Fight Night 104 on Fox Sports 1.

Jung is popular among hardcore fans and has been out since mid-2013 because of mandatory military service at home in South Korea, but his Octagon return isn't going to do significant business.

A week after that on February 11, the organization’s first PPV event of 2017—UFC 208—will soldier on with its head-scratcher of an inaugural women's featherweight championship fight between Holly Holm and Germaine de Randamie.

Ideally, the UFC wanted Cris "Cyborg" Justino opposite Holm in that bout. First, though, it couldn't come to terms with her on a schedule. Then, Cyborg reportedly failed a UFC drug test, according to the league's official site.

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As a result, the organization is stuck with the main event of Holm vs. de Randamie—an interesting fight that just won't move the needle.

From there, it will rinse and repeat throughout the first quarter of 2017.

At the moment, UFC 209 on March 4 shapes up as one of the period's brightest spots. It will feature Tyron Woodley's welterweight title rematch with Stephen Thompson and Tony Ferguson's interim lightweight title fight against Khabib Nurmagomedov.

Still, even with dueling championship fights on the card, UFC 209 won't do anything close to a Rousey, McGregor, Lesnar or Jones number on PPV.

This, in turn, brings up another problem facing the UFC to begin the new year.

Not only are a good number of its bankable stars AWOL, but 2016 left it with a slate of largely new and unproven champions.

The UFC experienced unprecedented turnover at its highest level last year. Twelve different fighters won titles or interim titles in seven weight classes. In its final months, 2016 descended into a dizzying maze of interim championships and spot matchmaking.

Now, the race will be on to see if any of these rookie titlists can become promotable entities. Nunes? Stipe Miocic? Cody Garbrandt? All seem to have potential, though the business of making new stars remains an inexact and sometimes unpredictable science.

Barring the sudden emergence of an unlikely superstar, numbers will likely be down during the first half of 2017. That means the second half of the year will need to shoulder a lot of financial weight once the UFC's established stars come back.

Will that be enough to offset a bleak couple of quarters? Unknown.

It should be noted the UFC has been here before. Ever since the generation of stars that included Chuck Liddell and Randy Couture hung up their gloves, the promotion has faced questions of how it would replace them.

To its credit, it has never panicked. Somehow, new standard-bearers have always come along.

In fact, despite the current confusion, the UFC's big-picture future remains bright. When we consider the possibility of this being a "down year," we're speaking in the most relative terms.

There's no doubt the company will remain profitable in 2017, probably hugely so. But overall profit goals might prove elusive, and that raises the question of how the UFC's new tastemakers at WME-IMG will respond.

Fact is, we don't know.

The head honchos from the Hollywood mega-talent agency have kept conspicuously low profiles so far, at least compared to the more audacious Fertittas. Not hearing from people like WME-IMG co-CEOs Ari Emanuel and Patrick Whitesell has allowed a note of the unknown to creep in.

The entire sport is striking into a new frontier, and the new landscape remains largely unmapped.

Right now, about all we know for sure is that the first half of 2017 may be rocky.