The Chin Index: Who Falls, Who Doesn't, and Why

Roughly 1 in 4 UFC veterans has never been knocked down.

In a sport built around the search for unconsciousness, more than 290 fighters with at least five UFC bouts have walked the cage for years without their feet leaving them. They have absorbed body kicks, taken elbows from the bottom, been hit by people who hit very hard for a living — and stayed standing.

One of them has done it 24 times.

Jon Jones has fought 24 times in the UFC and has never been knocked down. Not by Daniel Cormier. Not by Alexander Gustafsson. Not by Ciryl Gane or Stipe Miocic. Twenty-four fights, more than 90 rounds of championship pressure, against a roster of light heavyweights and heavyweights with double-digit knockouts on their résumés — and the canvas has never met the back of his head.

That's not normal. That's the top of an axis nobody has named yet.

We built that axis. We're calling it the Chin Index — knockdowns absorbed per UFC fight — and it splits the sport into people who fall and people who don't, with surprising sharpness about who ends up unconscious and who doesn't.

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I. The Chin Index

The metric is simple: how many times across your UFC career has the opponent's row in the round-stats sheet recorded a knockdown against you, divided by how many UFC fights you've had. Lower is better. Zero is perfect.

The distribution is brutal at both ends.

Bucket	Fighters	Share	Notes
0.00 (never knocked down)	296	23.7%	The clean record
0.01–0.10	111	8.9%	A single knockdown across a long career
0.11–0.20	331	26.5%	The league average band
0.21–0.30	201	16.1%	Starting to get knocked down
0.31–0.40	153	12.2%	A rough chin
0.41–0.50	81	6.5%	The danger zone
0.51–0.70	58	4.6%	Glass-adjacent
0.71+	19	1.5%	True glass jaws

The league mean is 0.205 knockdowns absorbed per fight. The median is 0.167. Almost a quarter of qualifying fighters sit at zero. Only 1.5% sit above 0.7 — and the people in that tier are the ones who define what a glass jaw looks like.

For the rest of this analysis, we apply a minimum of 10 UFC fights to the leaderboards. Anything thinner is sample-size noise — one bad night can swing a 4-fight career to a 1.00 Chin Index without telling us anything about the fighter underneath it.

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II. The Glass Jaws

The top of the Chin Index leaderboard is a mix of three populations: explosive prospects who washed out, journeymen who took on tougher and tougher opposition, and a couple of legends whose reputations don't match what the data records.

Rank	Fighter	KD/Fight	KDs Absorbed	KO Losses
1	Thomas Almeida	0.80	8 in 10	3
2	Keith Jardine	0.77	10 in 13	4
3	Antônio Rodrigo Nogueira	0.73	8 in 11	3
4	Sergio Moraes	0.71	10 in 14	3
5	Dominick Cruz	0.70	7 in 10	2
6	Nate Quarry	0.70	7 in 10	2
7	Matt Frevola	0.67	8 in 12	4
8	Antonio Silva	0.64	7 in 11	7
9	Dan Henderson	0.61	11 in 18	3

Thomas Almeida sits on top of the worst list in the sport. The Brazilian was one of the most talked-about bantamweight prospects of the 2010s — a viral knockout artist with a 22–1 amateur and pre-UFC record — and his UFC tenure was a brutal lesson in what happens when explosive striking meets opposition that hits back. He absorbed eight knockdowns across ten UFC fights. Three of those nights ended with the referee waving it off.

Dominick Cruz is the entry that shouldn't be on this list. A four-time UFC champion. The most technical footwork the bantamweight division has ever seen. The fighter who pioneered movement-based striking in MMA. And his Chin Index is 0.70. The reason: when the head movement fails — and against the very best, it sometimes does — he doesn't have the structural defense to absorb a clean shot. Cody Garbrandt put him down twice. Henry Cejudo finished him. The footwork either works completely or it fails completely. The Chin Index sees the failure mode.

Antonio "Big Foot" Silva is the most efficient glass-jaw conversion on the list: seven knockdowns absorbed across 11 fights, and seven KO/TKO losses. Every time Silva went down, the fight ended. Cabbage Correira had a higher absorbed rate; nobody had a more direct line from canvas to defeat.

The myth-buster is Nogueira. PRIDE's "Minotauro" was famous for absorbing punishment that should have ended other men's careers — the Mirko Cro Cop fight, the Bob Sapp fight, the Heath Herring trilogy. But by the time he reached the UFC, the durability that defined his prime was largely gone. UFC Nogueira absorbed eight knockdowns in 11 fights, lost three by knockout, and watched his chin curve toward zero in slow motion as his thirties became his forties.

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III. The Iron Chins

The opposite end of the leaderboard is the most surprising visualization in this article. Jon Jones is alone at the top. Twenty-four UFC fights. Zero knockdowns recorded against him.

Rank	Fighter	UFC Fights	KDs Absorbed	KO Losses
1	Jon Jones	24	0	0
2	Pedro Munhoz	22	0	0
2	Tim Elliott	22	0	0
2	Michael Chiesa	22	0	1
5	Gillian Robertson	20	0	1
6	Raquel Pennington	19	0	1
6	Tecia Pennington	19	0	0
6	Rose Namajunas	19	0	1
6	Anthony Johnson	19	0	1
10	Marvin Vettori	18	0	0
10	Amanda Nunes	18	0	1

Jon Jones has fought Daniel Cormier twice, Alexander Gustafsson twice, Mauricio Rua, Glover Teixeira, Lyoto Machida, Vitor Belfort, Rashad Evans, Stipe Miocic, Ciryl Gane, Dominick Reyes, Thiago Santos, and Anthony Smith. Some of those men have double-digit UFC knockouts. None of them have a knockdown on Jones. The closest is the Reyes scare in 2020 — a fight Jones nearly lost on points — and even there, the punches that landed never put him down. Jones's reputation is built on creativity, range management, and championship reigns. The Chin Index says it's also built on something more boring and more important: he does not get hit clean.

Anthony Johnson is the most poetic entry on the list. "Rumble" was one of the heaviest hitters in light heavyweight history — a 57.9% career KO rate, finishes of Glover Teixeira and Antônio Rogério Nogueira and Phil Davis. He knocked other people out. He was almost never knocked down himself. He finished his career with 19 UFC fights, one TKO loss, and zero knockdowns absorbed — a 95th-percentile chin on a 99th-percentile puncher.

Amanda Nunes holds the women's record for the cleanest defensive sheet over a long career. Eighteen fights, knockouts of Cris Cyborg and Ronda Rousey and Holly Holm, only one stoppage loss — a submission to Julianna Peña at UFC 269 in a fight where the canvas remained unbothered on either side.

The technical commonality across this list isn't a single style. Jones is a range striker with elite grappling. Munhoz is a pressure boxer with iron defense. Chiesa is a grappler who avoids exchanges. Vettori is a southpaw who walks forward through whatever you throw. What they share is the absence of the bad night. A knockdown is one moment. These fighters have built careers without that moment.

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IV. The Survivors

There's a third category the Chin Index reveals — the most interesting one editorially. Fighters who absorbed multiple knockdowns and survived every single one of them. Not just durable. Not just unfinishable. Re-emergent.

Fighter	KDs Absorbed	Fights	KO Losses
Kelvin Gastelum	9	26	0
Mateusz Gamrot	5	13	0
Rob Font	5	21	0
Francisco Trinaldo	5	26	0
Davey Grant	4	16	0
Julianna Peña	4	12	0

Kelvin Gastelum has been knocked down nine times in the UFC and has never been finished by strikes. Nine. Across 26 fights. Four of those knockdowns came in one fight against Israel Adesanya; the other five are spread across bouts with Joe Pyfer, Jared Cannonier, Rick Story, and Vicente Luque. In every single case, he was on his feet again before the referee could close the distance. Gastelum is the embodiment of the survival end of the Chin Index: high exposure, perfect recovery.

Julianna Peña has absorbed four knockdowns across 12 UFC fights — three of them in a single round of the Nunes rematch at UFC 277 — and has never been finished by strikes. She is the only fighter in UFC history to upset Amanda Nunes by stoppage, then walk into the rematch and absorb three knockdowns in the second round without going out. The Chin Index doesn't capture the look on her face when she stood back up. It just records four KDs absorbed and zero strike-stoppage losses.

The Survivors list is the part of the metric that pure absorption rate misses. A 0.50 Chin Index with zero KO losses tells you something completely different than a 0.50 Chin Index with five. Both fighters get hit clean half the time they enter the cage. One of them always gets up. The other doesn't.

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V. Division by Division

The conventional wisdom is that heavier divisions are more dangerous — bigger fighters generate more force, more force produces more knockouts. That logic holds for who throws the finishing blow (see The Knockout Artist — heavyweight KO rate is 51.5%, nearly four times women's strawweight). But the chin side of the equation tells a different story.

Division	KD/Fight	KO Loss %	Notes
Strawweight	0.088	7.8%	The safest canvas in the UFC
Flyweight	0.135	7.7%	Speed offsets power
Bantamweight	0.171	9.3%	The pivot point
Lightweight	0.201	13.7%	League average
Featherweight	0.217	12.8%
Heavyweight	0.221	21.5%	Bigger gloves, bigger margins
Light Heavyweight	0.223	19.5%
Welterweight	0.228	13.8%
Middleweight	0.228	16.5%	The peak danger zone

The men's divisions are remarkably flat. Featherweight through Heavyweight all cluster between 0.20 and 0.23 knockdowns absorbed per fight. That's a ~15% spread between the lightest 145-pound men and the largest heavyweights. The KO conversion rate diverges much more sharply (Heavyweight 21.5% vs Bantamweight 9.3%), which is the real story: heavyweights don't get knocked down dramatically more often, but when they do, the fight ends.

The cleanest cliff is at the women's end. Strawweight (0.088) and Flyweight (0.135) sit dramatically below the men's cluster — partly a function of fewer career fights per fighter, partly a function of the punching power on offer. Whatever the cause, the data says women's strawweight is the toughest division in the UFC to drop somebody in.

The intuition that "heavier division = worse chin" is half right. Heavier division = worse outcome from being dropped. The probability of getting dropped in the first place is remarkably stable across the men's roster.

A methodology note. Division above is assigned by each fighter's listed walking weight, so the 125-lb Flyweight row blends men's and women's flyweights, and the 135-lb Bantamweight row does the same. If we instead bucket by weight_class on each individual bout, men's flyweight rises to ~0.22 KD/fight (in line with the rest of the men's divisions) and men's bantamweight rises to ~0.23. The "women's end is cleaner" framing holds either way — but the cleanness lives almost entirely in the women's divisions, not in the lower men's brackets.

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VI. Does the Chin Age?

The cliché says fighters lose their chins in their mid-thirties. Coaches will tell you a fighter who used to absorb everything starts going down at 34, at 36, at 38 — the engine that processes impact stops working as well, and the next clean shot drops them.

The data agrees, but more gently than the folklore.

Age	KDs Absorbed / Fight	Sample (fight-observations)
18–24	0.146	1,544
25–27	0.176	3,492
28–30	0.205	4,739
31–33	0.231	4,051
34–36	0.267	2,330
37–39	0.298	823
40+	0.335	263

From age 18 to age 40+, the Chin Index climbs from 0.146 to 0.335 — it more than doubles. The curve is smooth, monotonic, and merciless: every age bucket is worse than the one before it. The chin doesn't fail at a specific birthday. It erodes from your first UFC fight until your last.

The cleanest fighters in the sport are the youngest. The 18–24 bucket at 0.146 KDs per fight is below every other group — and below every men's weight class above flyweight. Part of that is selection (fighters who get knocked down early often don't make it to a long career). Part of it is physiology (younger nervous systems take impact better). Either way, the data agrees with what every coach and cutman has been saying about why fighters should make the most of their twenties.

The bigger jump isn't where the cliché puts it — there's no sudden cliff at 35. It's a steady climb every three years: roughly +0.03 KD/fight every age bucket. By 40+, the average fighter sits at twice the rate of their early-twenties self. Dan Henderson finished his UFC career in this band — and posted a Chin Index of 0.61 across an 18-fight tenure largely fought in his late thirties and forties.

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VII. Does the Index Actually Predict Anything?

The whole point of building a metric is to verify it tracks the outcome it claims to measure. We plotted the Chin Index of every fighter with 10+ UFC bouts against their career KO/TKO loss rate. The Pearson correlation between the two is r = 0.59 — a strong, statistically significant relationship.

In plain English: the more knockdowns you absorb per fight, the more likely your career ends in a strike-stoppage loss. The line isn't deterministic — Kelvin Gastelum sits at 0.346 KD/fight with zero KO losses, and nobody can explain how Mark Hunt absorbed what he absorbed and stayed conscious — but the trend is unmistakable. Fighters with high Chin Indexes lose by KO at much higher rates. Fighters with clean chins almost never do.

The chart's bottom-left quadrant — low Chin Index, low KO loss rate — is dominated by the iron-chin list: Jones, Munhoz, Vettori, Anthony Johnson, Amanda Nunes. The top-right quadrant — high Chin Index, high KO loss rate — is where the careers ended early: Antonio Silva (0.64 / 64% KO loss rate), Thomas Almeida (0.80 / 30%), Julian Erosa (0.56 / 39%). The top-left quadrant is the rarest and most interesting — high Chin Index, low KO loss rate — and it's where the Survivors live.

This is also why we ship the Chin Index inside our v4 fight forecast model. When we rebuilt the model in May 2026, the strongest single new feature was knocked-down-per-fight — at +0.70 percentage points of permutation importance, it was the most valuable defensive variable we tested. The Chin Index is real signal. The model trades on it. The article is the metric stepping out from behind the model.

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VIII. The Active Watchlist

The Chin Index also works as a leading indicator on currently active fighters. The list below ranks the most concerning recent trends — fighters whose last five UFC fights show a Chin Index well above their career baseline. These are the active careers most likely to end with a strike stoppage in the next 18 months if the trajectory holds.

Fighter	Recent KD/Fight (last 5)	Career KD/Fight	Last Fight
Gilbert Burns	1.00 (5 KDs / 5 fights)	0.48	2026-04-18
Beneil Dariush	1.00 (5 KDs / 5 fights)	0.35	2026-05-02
Mackenzie Dern	1.00 (5 KDs / 5 fights)	0.38	2025-10-25
Eryk Anders	1.00 (5 KDs / 5 fights)	0.45	2026-03-14

Gilbert Burns is the most dramatic curve. His career Chin Index is 0.48 — already in the upper tier. His last five fights sit at 1.00 — a knockdown every time he walks in. The opening round of his April 2026 bout flagged it. The pattern is what we'll be tracking through 2026 — and it's the kind of trend that should affect his odds going forward.

Beneil Dariush has been in a UFC career-altering slump since his loss to Charles Oliveira; his Chin Index over the last five fights is nearly triple his career baseline. Mackenzie Dern's recent stretch has been the most defensively concerning in her career — she has long been a takedown-first fighter, but her recent striking exchanges are increasingly ending with her on her back for the wrong reason.

The watchlist isn't a prediction. It's a yellow flag. Some of these fighters will reset. Some will fall off the leaderboard the way Almeida did — quickly, and out of the cage.

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IX. What the Chin Index Says

We started by naming an axis. We end with a tier list.

The Iron Chins — Jon Jones, Anthony Johnson, Marvin Vettori, Amanda Nunes, Pedro Munhoz. Fighters who built long careers without the bad night. The most exclusive club in the sport, and the cheapest insurance an MMA bettor can buy.

The Survivors — Kelvin Gastelum, Julianna Peña, Rob Font. Fighters who absorb knockdowns and refuse to let them turn into stoppages. The category the metric exists to name.

The Glass Jaws — Thomas Almeida, Antonio Silva, Dominick Cruz, Sergio Moraes, Keith Jardine. Fighters whose exposure has, statistically, eventually caught up with them. The end of every glass-jaw career looks the same: a clean punch, a referee waving it off, and the data sheet recording the moment.

The Chin Index doesn't replace film study, doesn't replace knowing how a fighter moves, doesn't replace watching the way a body absorbs impact. But it's the cleanest one-number snapshot we have of who falls — and who doesn't. Across every era, every weight class, every style. One column. Two and a half thousand fighters. A 0.59 correlation with the outcome that defines this sport.

Jon Jones has fought 24 times in the UFC and has never been knocked down.

That, more than the wrestling, more than the elbows, more than the reach, is the part of his record nobody can take from him.

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Based on analysis of 40,972 UFC fight-rounds across 8,688 fights and 2,681 fighters, spanning 1993–2026.

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