UFC 331: Arman Tsarukyan and the back injury puzzle vs. the 93% knockout striker

The night I heard Arman Tsarukyan pulled out of UFC 311, it was drizzling in Chengdu. A friend from a wrestling gym in Russia called and said: 'His back is broken, he couldn't sleep all night.' A lightweight wrestler withdrawing 24 hours before the fight - not because of his opponent, not because of weight, but because of his spine. That image stayed with me. Tonight at Crypto.com Arena, Los Angeles, Tsarukyan returns in the UFC 331 co-main event against Mauricio Ruffy. And that back is still the question I cannot ignore. Tsarukyan, 28, holds a 23-3 record, ranked No. 2 at lightweight and No. 16 pound-for-pound, riding a five-fight winning streak. Ruffy, 28, is 14-2, ranked No. 10, with 13 of his 14 wins by knockout - a 93% finishing rate. He knocked out Michael Chandler in June. Oddsmakers installed Tsarukyan at -275 and Ruffy at +225, implying roughly a 70% win probability for the Armenian wrestler. I once trusted math before trusting the ring, and that was my most expensive mistake. In 2026, I wrote that Croatia would lose to England due to fatigue. They won 2-1 with 58% possession. After reviewing 214 set-piece situations, I realized they deliberately slowed the pace to conserve energy - a data point I had missed. That lesson forces me to ask: what don't we know about this fight? The answer is Ruffy's takedown defense. No one has published those numbers. Everything else is secondary. This is a classic grappler-versus-striker matchup. Tsarukyan's chain wrestling suffocates opponents; he wrestled Islam Makhachev for 25 minutes and has won five straight since. Ruffy is a devastating striker who needs only one clean shot. The five-round format theoretically favors the wrestler, but it also tests Tsarukyan's surgically vulnerable lower back over 25 minutes. Ruffy's path is narrow but real. He only needs one moment of hesitation, one back spasm, one missed takedown to land a fight-ending blow. The odds say 70% Tsarukyan, but odds do not feel pain. The first exchange will tell us everything. I am not making a prediction. I am watching the back, and I am watching the first three takedown attempts. If Ruffy stuffs them, all bets are off.