UFC Betting Explained: Favourite Bias & Underdog Bias

Favorites in UFC win much more often than underdogs, but that doesn't mean blindly betting either side is positive expected value. The real edge comes from understanding two biases: casual bettors over-love both short favorites and romantic longshots, and markets systematically misprice certain odds ranges because of that psychology.

The public bets favorites because they "feel safe." The public bets longshot underdogs because they "dream big." Both approaches lose money when done emotionally instead of systematically. Your edge comes from knowing when favorites are actually underpriced and when underdogs offer genuine value versus lottery-ticket delusion.

Read more: The Complete Guide to UFC Betting Psychology

What the Numbers Actually Say

Over the last decade, UFC favorites have won about 65.5% of the time, while underdogs won 34.5%. Another long-term sample of 709 fights found favorites winning 68.1% versus dogs at 31.9%, almost exactly matching what the closing odds implied (68.1% expected).

By division and year, the baseline is similar. In 2020, favorites went 37-19-1 (approximately 65%) with marginal profit or small loss depending on division and price bands. Some divisions like welterweight showed favorites at -185 or better as slightly positive expected value over specific periods, while dogs at certain weights like women's flyweight were more profitable during stretches.

So favorites win roughly two-thirds of the time. Dogs win about one-third. Books are very good at pricing that baseline. The bias, and your edge, lives in how bettors interact with those prices, not the raw win rates.

Shurzy Tip: The books aren't guessing. Their 68% implied probability on favorites translates to 68.1% actual win rate over thousands of fights. Your edge doesn't come from "favorites win more" or "underdogs hit sometimes." It comes from finding the specific matchups where the market is wrong.

Favourite-Longshot Bias in MMA

The classic favorite-longshot bias exists across many fixed-odds markets: big underdogs are usually overpriced (worse value than they appear), while big favorites are often underpriced (slightly better value than they appear).

How It Works

If a fighter is priced at +900, their implied win chance is about 10%. But in practice, their true chance might be closer to 3-5% in most matchups. The public is overpaying for the dream.

Conversely, a -300 favorite (75% implied) might have a "true" win probability near 78-80%, meaning the favorite is actually a bit cheap, not expensive.

MMA-specific data backs this up. In the +900 or above range, underdogs went 3-11 in one 10-year UFC sample (21% win rate, but heavily skewed by just a few famous shockers). Other longshot bands like +567 to +900 won only approximately 7% with -44% return on investment over 84 fights.

The deepest longshot bands generally show the worst long-term ROI. More moderate underdogs (+150 to +122, with 763 fights) provide more stable data and tend to perform closer to expectation.

Key idea: the more "lottery ticket" the underdog, the more likely the public is overpaying for the dream upset. Books don't mind writing those tickets because they know the math crushes lottery-ticket bettors over time.

How Bettors Misuse Favorites

Recreational bettors gravitate to favorites because they "feel safer," especially in main events and on parlays. They often bet favorites just to win, ignoring whether the price is fair. A -250 line might be justified, but a -600 line for the same true edge is not.

Parlays turbocharge this dynamic. People pile multiple favorites together for a big payout, pushing those chalk lines shorter than they should be. The books love this because parlay math exponentially increases house edge.

The Historical Reality

Blindly betting favorites still loses money in most sports, but the ROI is less bad than blind longshot betting. A football backtest using Pinnacle closing odds showed favorites at -2.21% ROI versus longshots at -4.47% ROI. MMA behaves similarly: favorites tend to be priced more efficiently than extreme underdogs.

Smart Favorite Use

Favorites are often slightly undervalued in aggregate because people prefer the excitement of dogs and longshot parlays, but many individual favorites are overcooked by hype.

The sweet spot is often moderate favorites (roughly -150 to -250) in spots where matchups clearly favor them and public isn't wildly distorting price. Divisional trend work has flagged things like "any favorite at -212 or better in lightweight was positive expected value over a 15-month window," illustrating how price bands and division tendencies matter.

Practical take: You are not "a square" for betting favorites. You're only a square if you're taking bad numbers because you refuse to pass. The sharp approach is betting favorites when they're underpriced and passing when they're overpriced, not blindly avoiding them because "betting chalk is boring."

Shurzy Tip: The best favorite bets are moderate chalk (-150 to -250) in matchups with clear stylistic advantages. The worst favorite bets are huge chalk (-500+) driven by name recognition and public hype. Know the difference and bet accordingly.

How Bettors Misuse Underdogs

Casual bettors love big underdogs for emotional reasons: big payouts, "what if" dreams, and social bragging rights when they hit. In UFC, that fandom is reinforced by highlight reels and narratives like Serra versus GSP, where a massive underdog shocked the world.

But aggregate data tells a different story. In the broad UFC sample, dogs win approximately 32-35% of fights and underperform slightly versus implied probability (expected approximately 34%, actual approximately 32%), with the gap largely representing vig. Extreme longshots bring the worst of it. While a few +700 to +900 shocks happen, the overall ROI on that band is deeply negative.

Where Underdogs Actually Work

Moderate dogs (around +120 to +200) often behave closest to fair value. This is where real matchup edges on the underdog can actually pay out without as much favorite-longshot distortion.

Some divisions like women's flyweight or welterweight in certain windows have shown sustained dog profitability due to volatile matchups and underestimated parity. Those trends are often time-bound, so you still need matchup context.

Practical take: Treat big dogs as rare, highly vetted shots, not as a regular diet. Focus dog action in the moderate ranges (+120 to +300) where your skill edge in reading tape and styles can cover the house edge and any residual bias.

Upset Dynamics: When Big Dogs Actually Hit

Historical analysis of 709 fights found upsets happen slightly more often on low-visibility portions of cards (Facebook and FightPass prelims) and least often on pay-per-views, where lines and matchups are most scrutinized.

ESPN's top 20 title fight upsets show 70% of those shockers ended by finish (knockout or submission), compared to approximately 50% overall finish rate. When huge upsets happen, they're more often violent finishes than razor-thin decisions.

Betting Implications

If you like a big dog, consider inside-the-distance and finish props at bigger prices. When big upsets hit, they often come via finish, not squeaked decisions.

Look for low-information fights lower on the card, where the market has less certainty and your tape work can uncover real value. The main event gets analyzed to death. The second prelim fight gets ignored. That's where edges exist.

Shurzy Tip: The biggest underdog upsets happen on prelims, not main events, and they happen via finish, not decision. If you're betting a +400 underdog, pair it with inside-the-distance props for bigger payouts when your read is correct.

How to Exploit Both Biases Without Being a Donk

Think in Odds Bands, Not Labels

Don't just think "favorite versus dog." Think in specific ranges:

Favorites:

• Short favorites: -120 to -200
• Medium favorites: -200 to -400
• Big chalk: -400 and worse

Underdogs:

• Small dogs: +105 to +200
• Medium dogs: +200 to +400
• Longshot dogs: +400 and longer

Then ask: Is this -500 favorite really closer to 80-85% than 83-84%? If not, pass or look for props. Is this +300 dog actually closer to 40% than 25% because of a stylistic edge? If yes, that's where you fire.

Use historical band ROI as context. The +900+ band is usually garbage. The +150 to +200 band is where most "real" dogs live. Adjust your expectations and bet sizing based on which band you're playing in.

Fight Your Own Emotional Impulses

If you feel an emotional high at seeing a big plus number, that's a red flag. Favorite-longshot bias lives exactly in that "this would be such a crazy story if" feeling. Your excitement about +700 odds is exactly why the books price them that way. They know you'll overpay for the dream.

Conversely, if you feel "bored" backing a -160, remind yourself that profitability doesn't care about excitement. The data says moderate favorites often carry better long-term expectation than sexy longshots.

Use Market Information to Sanity-Check Your Bias

Check opening versus current lines and public splits. If a dog you like has been hammered by sharps (line moved from +200 to +150 despite public on favorite), your underdog lean is likely well-founded. If a giant dog is stuck at +700 with no movement despite a week of publicity, assume the market is comfortable letting people donate on them.

Matchup First, Label Second

Decide who you think wins how often based on tape and data before looking at the price. Then compare your probability to implied odds:

• Favorite at -200 (66.7% implied) you think wins 75% of the time? That's a bet.
• Dog at +250 (28.6% implied) you think wins 40%? That's a bet.
• Favorite at -500 (83.3% implied) you think wins 80%? That's a pass (overpriced).
• Dog at +700 (12.5% implied) you think wins 8%? That's a pass (overpriced longshot).

This keeps you from auto-betting the "side" you emotionally prefer. You're betting mispricing, not favorites or underdogs.

Shurzy Tip: Build your model without knowing the odds. Estimate win probabilities from tape, then compare to implied odds. If you're building your model after seeing the line, you're anchoring to the market instead of independently evaluating the fight.

Bankroll Discipline: Same Rules, Different Labels

Whether favorite or dog, keep stakes within 1-3% of bankroll per bet. Longshots don't deserve bigger units just because they're exciting. If anything, they deserve smaller ones because variance is higher.

Parlays amplify longshot bias. Be very selective about adding big dogs or huge favorites to "juice" tickets. Books make much of their profit from this behavior. Every parlay leg you add exponentially increases house edge, and the more extreme the odds on each leg (huge favorites or huge dogs), the worse your expected value becomes.

Conclusion

Favourite bias means people overbet favorites emotionally, but markets price them relatively efficiently. Moderate favorites can be slightly underpriced. Huge favorites can be overcooked when public piles in.

Underdog bias means people love longshots and Cinderella stories. Extreme dogs are usually terrible value, but moderate dogs in the right matchups are where real upside lives.

Use the biases as context and a warning system. If you're drawn to a side because "everyone says the favorite is a lock" or "this +700 would be insane if it hits," stop and force the math. Your job is not to be Team Favorite or Team Underdog. It's to be Team Misprice. Bet the side where your probability estimation differs most from implied odds, regardless of whether that's the favorite or the dog.

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