UFC 331: Arman Tsarukyan Is the Favorite, but Mauricio Ruffy Is the Unpriced Variable

When the UFC announced that the lightweight co-main event between Arman Tsarukyan and Mauricio Ruffy would be scheduled for five rounds, I wrote a short line in my coded notebook: the promotion rarely elevates a co-main event to five rounds unless it wants that fight to produce the next title contender. The bout takes place at Crypto.com Arena in Los Angeles, with Jason Herzog — one of the most experienced referees in American MMA — in charge. Lightweight, 155 pounds, both fighters in the physical prime of their careers, and the prize behind it all is a shot at the reigning champion. That is what I recorded before sitting down at the numbers desk. Now let us get into the data. A QUEUE THAT IS JAMMING UP Arman Tsarukyan is ranked No. 2 at lightweight, tied with Ilia Topuria, and No. 16 in the pound-for-pound rankings. His record is 23-3 with a five-fight winning streak. Mauricio Ruffy sits at No. 10 at lightweight with a 14-2 record, and the headline item on the Brazilian's file is a knockout win over Michael Chandler — a result that lifted his name out of the rankings' shadows and into the major news feeds. The current lightweight contender list is deeper than the number of available title shots. Tsarukyan, Ruffy, Topuria and Justin Gaethje all sit inside the calculation. A five-round co-main event at lightweight is a clear organisational signal: the UFC is reshuffling its title queue and wants this result to speak instead of negotiating rooms. One note on the reliability of the information is necessary. Most of the details concerning the reigning champion's status in MMA Fighting's original live blog are written in running-report form and could not be cross-checked against the official rankings at the time I finished this piece. Following my habit of verifying every number against at least two sources before publishing, I have to flag that section as "pending verification", and I will return to it at the end. GRAPPLER VERSUS STRIKER: THE CLASSIC MATCHUP This is the classic matchup shape of mixed martial arts: a fighter with a wrestling base against a stand-up specialist. Ruffy has won 13 of his 14 victories by knockout or technical knockout, roughly 93 percent. At lightweight — where the divisional knockout rate is far lower — that figure sits outside the normal distribution. He needs only one clean moment to end the fight, and that is a weapon that does not require many opportunities to detonate. Tsarukyan arrives with the opposite weapon: chain wrestling, control time on the mat and an imposing pace. His recent submission win over Dan Hooker is evidence that the wrestler has maintained his form inside his own weight class. He has even competed in freestyle wrestling at RAF, a non-MMA wrestling venture — a detail showing the UFC is allowing high-value contenders to appear in cross-discipline events, both to earn extra income and to keep their grappling sharp. The market has read this gap very clearly. The FanDuel line has Tsarukyan at -275, with Ruffy at +225. Converted roughly, -275 implies about a 73.3 percent win probability. After stripping out the bookmaker's margin, the fair line lands near 70 percent. In other words, the betting market judges the grappling gap to be larger than Ruffy's one-punch power. Numbers do not lie; we simply have not asked them the right way. In the original live blog I could find Ruffy's knockout rate, Tsarukyan's five-fight streak, the odds, the rankings, the round count — but not a single figure on Ruffy's takedown defence. That is the decisive variable of this fight, and it is absent. For a wrestler, the winning script runs through taking the fight to the mat. If Ruffy stays vertical, his 93 percent knockout rate retains its full value. If he does not, the fight flows into Tsarukyan's control zone and the one-punch power becomes an unusable asset. The five-round format tilts further toward the wrestler. A fighter with a control-based pace accumulates advantages over time; the best window for a knockout hunter usually sits in the early rounds. This matchup shape also produces a familiar pattern: the live underdog. A striker with a near-93 percent knockout rate needs only one clean exchange against a wrestler whose stand-up defence is the weakest phase of a grappler's skill set. Drawing on my own experience covering lightweight fights over many years, I always check three things before trusting a favourite's line: the opponent's takedown-defence rate, the wrestler's injury history, and the scheduled round count. Two of those three are in the original piece. The first is not. THE DEBT FROM UFC 311 On January 17, 2026, one day before UFC 311, Tsarukyan withdrew from a title fight against Islam Makhachev because of a back injury. For a wrestler, that is the injury category that strikes the core weapon directly: takedowns, mat returns, top pressure. The original live blog mentions the episode as a line of historical context, accompanied by a somewhat wry joke about how nothing could possibly go wrong. I keep that note. The recent five-fight streak confirms Tsarukyan has returned and won, but it says nothing about how his back is operating through repeated level changes and chain takedown attempts. If the problem is chronic, the career curve of a 28-year-old could flatten earlier than his age would allow. This is also why I do not entirely agree with how the market has priced the fight. Seventy percent for the favourite is reasonable on historical grounds, but it assumes the injury variable has been fully priced in. Meanwhile, against a heavy-handed opponent like Ruffy, the underdog's equity is not small: he needs one clean exchange. Before asking who wins, ask who keeps discipline. For Tsarukyan, discipline means not standing in extended exchanges. For Ruffy, discipline means not being dragged to the mat in the early rounds — precisely the window when a wrestler is freshest. A NOTE ON THE MARKET The fact that a major outlet is running live coverage of a co-main event shows the commercial weight of the lightweight division. The segment that benefits most directly from fights like this is data and betting: a bout with a clear two-way line generates heavy tracking money, and the -275/+225 split is the market's condensed expectation. I monitor these figures as an indicator, not as betting advice in any form. WHAT TO TRACK Three signals first: whether Ruffy can stay vertical through the opening takedown attempts; whether Tsarukyan's level-change explosiveness holds up; and whether the odds drift away from -275/+225 before fight time. For me personally, the third signal usually originates in medical information channels that the press cannot access. The fight ends, but the data does not. If Tsarukyan wins the way he has won his last five, the lightweight title queue will have one clear name in it. If Ruffy lets his hand detonate, the lightweight rankings will have to be rewritten from the top. Both scenarios already sit in my notebook, waiting to be circled in red ink.