Proposition Betting Strategy

In sports betting on a proposition, also called a prop bet or a prop, a wager is placed on anything other than a point spread, moneyline or game total. Exactly what this wager might be is anything from which team will score first, to which quarterback will have the most passing yards, to any other scenario described by a betting site.

This form of wagering is generally considered the easiest to beat. To support this, Las Vegas’ number one sports book for prop wagers, the Las Vegas Hilton, has gone on record many times claiming that Las Vegas sports books frequently lose money on prop bets. Meanwhile, many betting sites willing to take $5K-$40K per bet on NFL sides limit props to $200 or $300 max bets.

The reason props remain the easiest wager to beat relates largely to careless bookmaking. Don’t get me wrong: this is not at all a knock on the bookmaker. With several hundred lines to create and manage, lines managers are content with simplistic methods and low betting limits for small market props. This means that it is quite possible for a serious low to mid-stake pro to analyze a single prop in far greater detail than the odds maker that created it. Meanwhile, the small max betting limit keeps the sharks away and allows for line movement based on recreational action. Careless bookmakers, no sharks, and lots of fish, sounds like a profitable market to me.

To make one thing clear about prop betting, the more smart bettors there are betting props, the lower the opportunity becomes. No one in their right mind is going to write a detailed guide to betting props. To learn, you’ll need to pick things up in bits and pieces. So, while you’ll need to do some digging to get to the point where you can analyze any prop offered, I’ll go ahead and get you started in the right direction. Here, I’ll cover a prop widely available for NFL football, “Which team will score first?”

To give this example, I’ll take my notes from the 2010 Thanksgiving Day game between the New England Patriots and the Detroit Lions. My first step in looking for value on the “which team to score first” prop was to shop as many betting sites as possible offering the line. These are the options I found:

Bookmaker.eu: Patriots -175 / Lions +145
Sportsbook.ag: Patriots -165 / Lions +135
Pinnacle: Patriots -147 / Lions +126
5 Dimes: Patriots -150 / Lions +130
The Greek: Patriots -170 / Lions +140

After grabbing the lines, I am rather optimistic. My choices are Patriots -147 / Lions +145 which is such a slim margin that if the lines moved any further, I’d have an arbitrage opportunity. I’m interested enough to take the next step.

If you’re not familiar with the term derivative, this is an important one in sports betting, and as you learn strategy, you’ll become quite familiar it. To give it to you simply, the prop bet we’re looking at “which team will score first” is a derivative, derived from the game’s first half betting lines. To analyze this prop further, I went line shopping on these as well and found:

Bookmaker.eu: Patriots -4 / Lions +4 (25)
Sportsbook.ag: Patriots -4 / Lions +4 (25)
Pinnacle: Pats -3.5 -116 / Lions +3.5 +105 (o24.5 -102 | u24.5 -108)
5Dimes: Patriots -4 -105 / Lions +4 -115 (25)
The Greek: Patriots -4 / Lions +4 (24.5)

Pinnacle and 5 Dimes are two sites that work hard to keep their lines accurate, where Sportsbook.com, Bookmaker and The Greek are more content with pricing each side at -110. These are the lines I want to pay the most attention to. Using a method I shared in my article on Future Betting, I calculate the no vig line at 5dimes as Pats -4 +104 / Lions +4 -104 and the no-vig line at Pinnacle as Pats -3.5 -110 / Lions +3.5 +110.

The proper method from here would be half-time push analysis of the favorite winning the first half by 4 points. With detailed research into this, I could convert the 3.5 line at Pinnacle into a 4 point base, average each line out and create a very accurate predicted first half margin of victory. Or, to keep things simple, I can just say: based on these two lines, the Lions are predicted to cover +4 slightly more often than the Pats cover -4; but when it gets closer to a 3.5 spread, the odds quickly shift in the Pats favor. Fractions of a percent will not matter much, so ball parking this as Pats -3.9 works fine.

As far as the total is concerned, the difference between 24.5 and 25 on a half point spread is extremely factional. In fact, examining 5 years of NFL data, not once has a half time score totaled 25 points. It’s an odd number that is difficult to get, based on 7 point and 3 point scoring intervals. In this spot, I’m going to trust Pinnacle and the Greek and go with 24.5, though I will loop back to it before making a bet.

What I have now is the Pats winning by 3.9 and a total combined score of 24.5 for the first half. With this info, I can subtract 3.9 from 24.5 and get 20.6. I give half those points to each team (10.3 each) and then add the 3.9 back in, giving it all to the Pats. What I end up with is a predicted score of Pats 14.2 Lions 10.3. This score has Pats winning by 3.9 points and a total of 24.5, so the prediction fits.

The next thing we need is the magic formula bookmakers use to get a moneyline out of a predicted score. For the favorite, that magic formula is: -100 * (Favorite Score / Underdog Score). In this example, the math is -100 * (14.2/10.3), which equals 137.8. If my calculations were correct, the true moneylines for which team will score first is Pats -137.8 / Lions +137.8.

Let’s look at the method we took a shortcut with earlier, the first half total. Pinnacle suggested the total should be slightly less than 24.5. Meanwhile, other betting sites had the total at 25. I’ll save showing the math here, but calculating this with 24.4 as the total score, I get Pats -133 / Lions +133, and calculating with 25 as the total score, I get Pats -138 / Lions +138.

Here, I’ve now calculated that the fair price on the Lions scoring first ranges from +133 to +138, and believe my +137.8 analysis is the most accurate. I’m confident enough now that Lions +145 is a +EV bet, so I go ahead and make that wager at Bookmaker.

After making this bet, I noticed something interesting. The 5 Dimes line Pats -150 / Lions +130. When backing vig out of this line, I realize 5 Dimes has the no-vig moneyline at Pats -138.1 / Lions +138.1. 5 Dimes is the hands down leader in the market when it comes to prop bets. They offer more props than any other betting site, and they also operate with the lowest margin (least vig). If I want my calculated true-value money to match any betting site’s no-vig lines, 5 Dimes is the site. Again, this is something I only noticed after making the bet, but it certainly increased my already high confidence level that Lions +145 was a +EV bet.

A Little About Derivatives

The prop bet we just analyzed was a two level deep derivative: Which team to score first is derived from the half time line, which is derived from the full game line. If you’ve read my article on the current betting market, you likely understand that the top level derivative here is the most efficient. The beautiful thing about derivatives in sports betting is that as the main market moves, derivatives follow at a slower pace. Going back earlier in the week to when this prop market first hit the board, the Patriots were favored by more points than they are now. The fact that a small-market level two derivative never fully caught up, combined with recreational bettors moving the line, are the reasons we were able to find this +EV bet. This is an article for another time, but one of the top ways to win in sports betting is to find slow moving derivatives. When you go forward to learning other props, look for ones that are as many derivatives deep as possible, and you’ll have an easier time quantifying your edge.