Whether it was due to the superstardom of Conor McGregor, the aftereffects of a $4 billion sale or a variety of other factors, 2017 was unlike any other year in UFC history.

Before we dive headfirst into 2018, let's look back at the key moments that shaped the organization in 2017.

Conor McGregor faced Floyd Mayweather in a boxing match in August, losing by TKO in the 10th round. Christian Petersen/Getty Images

1. Conor McGregor boxes Floyd Mayweather in Las Vegas (August)

The whole thing was surreal. Even now, nearly five months later, you can almost convince yourself it never happened. It couldn't have, right? Surely, the UFC did not lend its 29-year-old lightweight champion to boxing, to serve as the final opponent to an undefeated Floyd Mayweather (sigh). Well, it happened. And yeah, it was a good bit of fun while it lasted. But as we enter 2018, with no assurances of when McGregor will fight again (or if he'll fight again), it doesn't really seem worth it. Unless you're McGregor.

Jon Jones defeated Daniel Cormier at UFC 214 for the light heavyweight title, but later failed a drug test. Gary A. Vasquez/USA TODAY Sports

2. Jon Jones reclaims light heavyweight throne, fails drug test (July)

MMA got to celebrate the return of Jones for nearly one month, before it was all taken away. Again. The fact is, MMA is so much better with Jon Jones. He's the kind of talent that only comes along once in a generation. He's interesting, in part because he's polarizing. And he's still only 30! His victory over a rival in Daniel Cormier was one of the best nights of the year. And the day the UFC announced he'd been flagged for a failed drug test was one of the worst. It's still unknown when he'll return.

Georges St-Pierre returned after a four-year layoff to claim the UFC's middleweight title from Michael Bisping. Jeff Bottari/Zuffa LLC/Getty Images

3. Georges St-Pierre wins middleweight championship, vacates it after one month (November)

A former welterweight champion returns from a four-year layoff, is gifted an immediate title shot at middleweight, wins, and then vacates that title 31 days later -- against the clear wishes of UFC president Dana White. Not only did this situation in New York affect the UFC's middleweight division in 2017, it exemplified the "Money Fight" era the UFC has entered. And, of course, it added to St-Pierre's legacy, possibly cementing him as the greatest of all time.

Khabib Nurmagomedov, left, was expected to face Tony Ferguson early last year but was forced to pull out at the last minute due to illness. AP Photo/John Locher

4. Tony Ferguson predicts Khabib Nurmagomedov's tough weight cut; Nurmagomedov later hospitalized (March)

The lightweight division was mostly stagnant in 2017. And while the majority of blame can be directed at McGregor, the events of March 2 didn't help. An interim fight between Ferguson and Nurmagomedov was scheduled for March 4 in Las Vegas. During a staredown two days before, Ferguson told Nurmagomedov, "Have fun with that weight cut." That night, Nurmagomedov was hospitalized due to complications of the weight cut. The fight never happened. Still hasn't. Maybe in 2018.

The UFC and its fighters honored those affected by a deadly shooting in Las Vegas last October. Joshua Dahl/USA TODAY Sports

5. Demetrious Johnson breaks UFC record at Las Vegas event shortly after mass shooting rocks the city (October)

An unforgettable event. Johnson broke Anderson Silva's record of 10 consecutive UFC title defenses -- and did it in style, submitting Ray Borg with a suplex-armbar no one had ever seen before. This event was bigger than just Johnson, however, as it occurred six days after a deadly shooting rocked the entire city. There was talk about canceling the event, but it ultimately went forward. The UFC honored victims and first responders throughout the night.

Jose Aldo, the longtime UFC featherweight champion, has lost three of his last four bouts -- two to Max Holloway. Josh Hedges/Zuffa LLC/Getty Images

6. The fall of Jose Aldo ... and the rise of Max Holloway (June, December)

Some will say the fall of Aldo took place in December 2015, when he was knocked out by Conor McGregor in just 13 seconds. But that's not the full story. Aldo bounced back in 2016 with a win over Frankie Edgar -- but when it became clear he wasn't getting a McGregor rematch, he grew bitter and has never looked the same. He spoke about wanting to box, and walking away from MMA. Holloway was all too willing to take Aldo's throne, finishing him twice, and appears poised to rule featherweight with an iron fist.

Cris Cyborg defeated Holly Holm by decision at UFC 219 on Dec. 30. Brandon Magnus/Zuffa LLC/Getty Images

7. Cris 'Cyborg' Justino fights Holly Holm (December)

This fight was years in the making. Not just Cyborg vs. Holm, but Cyborg vs. "someone with even the slimmest of a chance." For years, this sport has watched Justino wallop one overmatched opponent after another. And for years, it praised her as one of the best fighters in the world while also wondering how much that had to do with her lack of quality opponents. Holm didn't win the fight, but she put up a fight -- and that alone was enough.

Rose Namajunas shocked the world when she knocked out Joanna Jedrzejczyk at UFC 217 in November. Jeff Bottari/Zuffa LLC/Getty Images

8. Rose Namajunas stuns Joanna Jedrzejczyk in New York (November)

Frankly, few thought Namajunas had a chance. And the ones who did weren't guessing it would be by knockout. There was no greater example of "rising to the occasion" in 2017 than Namajunas' win over Jedrzejczyk. She turned the tables on Jedrzejczyk's prefight intimidation tactics and knocked out the feared striker in under one round. You consider the opponent, the event, the venue, the pressure on Namajunas in this fight -- to give that kind of performance? Remarkable.

Light heavyweight Daniel Cormier won't feel like a real champion unless he defeats Volkan Oezdemir on Saturday. Kevin Hoffman-USA TODAY Sports

9. Daniel Cormier's 'Towelgate' (April)

Welp. Cormier ruined it for everyone. The "towel trick" can never be used again. Prior to his light heavyweight title defense against Anthony Johnson at UFC 210 in Buffalo, Cormier initially missed the 205-pound championship weight by 1.2 pounds. Complete disaster. But then, Cormier disappeared for two minutes, resurfaced and, lo and behold, weighed 205 pounds. Was it a miracle? No. Cormier, who had disrobed to shed every pound, blatantly pressed down on an outstretched towel in front of him. The New York commission missed it, and it approved the weight. Months later, it rewrote some of its own rules to prevent a future repeat. If you ain't cheatin', you ain't tryin'.

Michael Bisping met Robert Whittaker in the Octagon after the latter defeated Yoel Romero at UFC 213. Josh Hedges/Zuffa LLC/Getty Images

10. Michael Bisping throws his own title at Robert Whittaker, storms out of Octagon (July)

High comedy. And arguably, one of the most symbolic moments of the bender that was Bisping's title reign. Look, Bisping is a legend. Future Hall of Famer. Warrior. One of the best professional fighters ever. But his time as a champion went completely off the rails. And this image of him inexplicably throwing his own belt at the feet of a legitimate challenger in Whittaker, who had just beaten Yoel Romero, then storming out of the cage was too perfect. Of course, Bisping never fought Whittaker. He went on to lose to St-Pierre, who also (symbolically) threw his own middleweight title at Whittaker's feet.