Conventional wisdom in sports betting is that some spreads (so called dead numbers) are less likely to be the final difference on the scoreboard, and so not all line moves are created equal. Given that scores mostly come in threes and sevens - with a few more sixes and eights than pre-2015 – it certainly seems reasonable.
Normally distributed?
The first thing to look at is how are scores distributed in the NFL. Here are two different graphs looking at how much the home teams win by (negative scores indicate the road team won):
In the left one, we’ve bucketed groups of scores together and the blue line represents a normal distribution. Looks pretty close. Once we break it down to individual scores though (right), we see that some scores are much more likely than others, in pretty much exactly the ways you would expect.
• Most likely are +/- 3 points. These account for about 15 percent of all game scores.
• Next up are +/- 7 points at about 9.5 percent of all scores
• Almost half of all games land on one of 6 numbers: 3, 7, 10, 6, 4, 14
Some numbers are much more likely than others
Not exactly breaking news. But how should we interpret a line move? Obviously, we pay the most attention to those near those common scorelines, but is it safe to ignore the in-betweens? And how to choose between getting -3 at -110 or -2.5 at -120? Let’s take a couple examples.
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Laying the key numbers
Six of the 15 NFL betting spreads for Week 5 games find themselves in the 2.5-3.5 point range. Five are giving three points while the Titans currently sit -3.5. How much does that half point matter? Since 2002, games with these lines have hit the 3-point mark 8.4 percent of the time. Not only is this worth shopping around for, it’s worth giving up a bit of extra vig for as well: a bet on -2.5 at -120 has outperformed a bet on -3 at -110 by about $3.50 on a $100 wager.
Meanwhile, the Rams and Panthers are laying a full touchdown while the Bengals and Saints currently sit -6.5. This half point hasn’t been as valuable as around the field goal – games in this range have hit seven a little over 5 percent of the time - but still barely worth a bit of extra vig and definitely worth shopping around for.
In the Dead Zone?
The Chargers and 49ers find themselves as home favorites in that traditional dead zone around five points. Can we mostly ignore line moves here until we get close to those key numbers? You can call me cheap – I’m used to hearing it – but I’m going to say no. These movements are certainly less valuable to sports bettors, a half point has been worth around $1.50 on a $100 bet. Don’t pay any extra vig, but in a game where you need to fight to have any edge it’s worth browsing.
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The Real Dead Zone
Lines between +/- 2 are relatively rare – about two per week historically – and Week 5 sees the Packers and Jets as 1-point favorites. I have trouble getting excited to shop around for that half point. The difference between +1 and +0.5 is less than $0.75 on a $100 bet and don’t get me started on 0.5 vs. pick’em.
The take home
News Flash: the line matters. Conventional wisdom on dead numbers has the right idea, but you should still be looking around for the best lines (always good to have multiple sportsbook accounts). Checking the Covers Live Odds page, many of the games discussed above have different lines at different books. Shop around and stick to your numbers. There are times where it’s worth paying a little extra vig for that half point - especially for lines around three - but in the dead(er) areas extra vig is to be avoided.
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