Sports Betting
ESPN.com staff 3y

Volume and volatility: How should you approach player prop bets?

NFL, Fantasy, null

Feeling intimidated looking at all the odds and props available? Do all of these numbers look like magic to you? Well have no fear, we've gathered our best sports betting and fantasy football minds to break down how they approach the season, how to apply fantasy projections to player prop bets and when you should bet the under.


1) There are many intersections between fantasy and prop betting. How do you approach a season-long prop from a betting point of view and what would be different looking at it from a projection/fantasy point of view?

Fantasy Football Writer Mike Clay: Step 1 is the easy part: Compare each projection to the corresponding prop and see which ones pop as values. Makes sense. But that's not the end of the discussion. Perhaps the most popular criticism of my projections as they are too low (or "too conservative"), but when compared to a full batch of props, I've found that I've actually been too high (or too aggressive) in certain areas. In fact, I'd argue that if you reviewed most projections across the industry, you'd find that a good 80% would be over the corresponding prop. Props are often a reminder that injuries, drop off and variance are understated as it pertains to fantasy advice. The key difference between fantasy and prop betting is that you can get away with focusing more on the ceiling in fantasy, whereas considering the floor is extremely important for betting props. Put another way, if you aim for upside in fantasy, it can pay off in a big way, whereas if your ratio of overs to unders in prop betting leans too far toward the former, you're likely going to come out with a net loss. 

Sports betting analyst Doug Kezirian: All bettors have their own approach and mine mostly stems from an old-school handicapping approach, which is basically applying sports knowledge and other general acumen. Of course, when you're assessing a season-long prop, you have to have a grasp for the statistic. For example, in MLB, if you ask me if someone will bat .300, I already have a general sense of what that means. But if you ask me if a wideout will go over or under 1250 yards in what is now a 17-game season, I have to crunch a few numbers to process the prop. In this example, that's 73.5 yards per game and I will then start to research past performance. None of this is too elaborate and oddsmakers obviously grasp the simple math, but it does help me apply a gut check and form a conclusion based on a general sense of what is expected on a game-by-game basis. My ultimate opinion will center around my opinion on that QB, any roster moves that impact the player's opportunity and how that team will fare that season. Additionally, in almost all situations, I will scour fantasy websites or source some math modelers to gauge the analytical projections (see below).

Sports betting analyst Anita Marks: Mike is spot on, but it is difficult to bet the under the majority of the time because we -- as sports "fans" -- want to bet the over and cheer for that player to perform well. Unless you are a Ravens fan, and then you take the under on Odell Beckham Jr.'s receiving yards. As they say in fantasy, you need to leave your heart at the door. In making prop bets, you need to do the same. Again...much easier said than done! Would it be a wise betting strategy to take the 10 highest season player props at each position (QB, RB, WR and TE) and bet the under on all of them?

Clay: The proof is in the pudding, right? I took a look at the Caesars Sportsbook props we referenced often throughout the past two offseasons. In 2019, the under hit on 90% of the top-10 pass TD props, 60% of the top-10 passing yardage props, 80% of the top-10 receiving yardage props, 50% of the top-10 reception props, 50% of the top-10 rushing yardage props and 60% of the top-10 total touchdowns props (20% were ties). In 2020, the league experienced a massive boost in offense and yet the under was still the play, hitting on 55% of overall props.

The under hit on 40% of the top-10 passing yard props, 70% of the top-10 receiving TD props and 60% of the top-10 receiving yardage props. We had a smaller sample of options in other categories, but the under hit on four of the top-five rushing yard props, three of the top-five rush TD props and three of the four available pass TD props.

2) How does a player's week-to-week volatility impact whether you bet on him or start him in fantasy?

ESPN Fantasy Senior Writer Eric Karabell: Well, I'm not sure it impacts it much, or if it should. Much goes into months of initial projections and it seems silly to tear 'em up after a week or two. During a season, after a substantial part of the season, I will reassess, but just because Patrick Mahomes has a rough Week 1 it does not alter my expectations for Week 2. Would we notice in Week 6? By the time the byes arrive, I reassess overachievers and underachievers. Also, football volatility is unlike baseball, for example, so take each sport differently with proper prop betting plans.

Marks: I like the volatility when it comes to betting weekly prop bets, because there is usually a reason behind it. For example, an injury, change in offensive scheme or game plan, a player in the offensive coordinator's doghouse, etc. Research the cause, under the effect and bet accordingly.

3) When looking at betting a prop to bet, how much do you use the fantasy projections?

Marks: We have the best fantasy analysts in the business, I'd be foolish not to. I also find the weekly/daily info write ups on each player to be very helpful in my analysis.

Kezirian: I concur with Anita but I also often apply this concept in a macro sense. If credible people are devoting time and effort to projections, I want to consider and process all of them. Obviously there is a point of paralysis by analysis, but I am a firm believer in aggregating information and considering all points. Ultimately you have to make your own decision but respecting differing opinions is a wise approach; tunnel vision is never beneficial. For example, if you are about to bet the over and two modelers you respect love the under -- and the analysis makes sense -- I probably will lay off. If the under hits, then I actually "made" +110 by avoiding the -110 loss.

4) As ESPN's projections creator, how do you narrow down the weekly props you're most confident in betting based on those projections?

Clay: The process is very similar to what I laid out earlier: I compare my weekly projections to the props and see which ones pop as values. Once I have a few in mind, I dive into the data to see if my projection is justified or if I need to make a tweak. Once I'm comfortable with a few props, those are the ones I jump on. Unlike season-long props, I'm more prone to lean toward overs for single-game props. Sure, there's more variance with smaller samples, but if you have a good feel for a player's projected volume or perhaps a very good (or bad) matchup, you can be more aggressive with over bets.

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