Where Is the Cutoff for Betting NFL Moneyline Underdogs?

Oct 4, 2022 - 4:10 PM

I recently wrote a piece on how much the spread matters when betting the NFL. Some people are calling it the greatest sports betting piece written in the past 12 hours.

I wouldn’t go that far, but you should check it out.

If you’re too busy to read it, I’ll bottom line it for you: Although it historically has been better to bet against the spread instead of on the moneyline when wagering on NFL underdogs, it has specifically been more profitable to use the moneyline — instead of the spread — on short underdogs.

In my piece, I singled out underdogs of +0.5 to +3, but someone on Twitter asked what the cutoff point was. How long can a short underdog get before it loses value on the moneyline relative to the spread.

Let’s look into it.

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NFL Spreads vs. Moneylines: Short Underdogs

To recap, here’s the data on short underdogs against the spread vs. the moneyline, from the Bet Labs database (available via Action Network), which goes back to 2003.

Abbreviations: Against the spread (ATS), return on investment (ROI), moneyline (ML).

ATS Underdogs: +0.5 to +3

• Record: 834-789-79
• Win Rate: 51.4%
• ROI: 1.6%
• Units: +27.2
• Margin: +0.67

That’s pretty good. But the moneyline is better.

ML Underdogs: +0.5 to +3

• Record: 768-930-4
• Win Rate: 45.2%
• ROI: 2.4%
• Units: +40.8
• Margin: -1.6

If you like a short underdog on the spread, you should at least consider betting the dog in the moneyline market — assuming you find a price that aligns with your numbers.

NFL Spreads vs. Moneylines: Underdogs Between a Field Goal & Touchdown

But what if you like an underdog of +3.5? Or +6.5? Has it still been historically profitable to pivot to the moneyline market in those situations?

Here are the numbers.

ATS Underdogs: +3.5 to +6.5

• Record: 835-808-19
• Win Rate: 50.8%
• ROI: -1.2%
• Units: -20.5
• Margin: -0.35

That’s not good at all. What about the moneyline?

ML Underdogs: +3.5 to +6.5

• Record: 567-1,091-4
• Win Rate: 34.2%
• ROI: 1.1%
• Units: +18.8
• Margin: -5.14

Fascinating. Moneyline underdogs of less than a touchdown and more than a field goal haven’t just outproduced their spread counterparts. They’ve been the difference between profitability and penury.

For underdogs in the spread market, between +3.5 and +6.5 has been a dead zone.

NFL Spreads vs. Moneylines: Underdogs of +6.5

In digging through the historical data, I’ve noticed a sizable surge in value at +6.5, which is an intriguing number because it sits between the two key numbers of +6 and +7.

After +3, the two most important numbers in terms of margin of victory are +6 and +7.

And I think there’s something about where +6.5 is situated and its proximity to those numbers that grants it excess value.

ATS Underdogs: +6.5

• Record: 126-107
• Win Rate: 54.1%
• ROI: 6.0%
• Units: +14.0
• Margin: -0.02

That’s fantastic value, as is this.

ML Underdogs: +6.5

• Record: 76-157
• Win Rate: 32.6%
• ROI: 11.7%
• Units: +27.3
• Margin: -6.52

My theory: Bettors generally avoid underdogs of +6.5 because they’re waiting for the line to move to +7. In essence, they anchor to the potential future value they will get if they bet the line at +7, and that prevents them from betting on a team they might otherwise be happy to back.

And in turn that lack of investment in these +6.5 underdogs means that the bookmakers don’t feel market pressure to move these teams from +6.5 to +6 or even lower. And so teams that might actually deserve to be shorter underdogs are instead stuck at +6.5.

At least that’s my theory.

But regardless of why +6.5 has historically offered so much value to underdogs, the fact is that there’s still value on the moneyline relative to the spread at this number.

NFL Spreads vs. Moneylines: Underdogs of +7

What about underdogs of a touchdown?

Nope. This is where we see the bottom fall out.

ATS Underdogs: +7

• Record: 161-162-20
• Win Rate: 49.8%
• ROI: -3.8%
• Units: -12.9
• Margin: -1.76

And this is where it gets worse for moneyline underdogs.

ML Underdogs: +7

• Record: 81-260-2
• Win Rate: 23.8%
• ROI: -11.8%
• Units: -40.3
• Margin: -8.76

That’s brutal.

For the moneyline, the move from +6.5 to +7 is massive. Yes, with that half point you theoretically capture more upside via longer odds. But in reality you move from one class of team to another — from a team that shouldn’t be an underdog of a touchdown to a team that should be an underdog of AT LEAST a touchdown.

My theory: The key number of -7 possesses significant gravity for favorites. It’s the Saturn to their moons. Lines that otherwise might move to -7.5 and beyond are pulled back to -7 and stuck there, because if oddsmakers move the line from -7 to -7.5 then underdog backers will immediately grab the +7.5 and drive it back down to +7, thinking that they’ve gotten the best of the number and some real value.

In actuality, all that they’ve gotten is a losing ticket. At least historically.

So +7 is the breaking point. At +0.5 to +6.5, there’s often value in attacking the moneyline — again, assuming that the odds you get correlate well with the spread.

But starting at +7, it has historically made more sense to bet on the spread, not the moneyline, when backing underdogs.

And, really, it has been most profitable to avoid underdogs altogether at +7 — or, instead, to bet against them.

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