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Daily Fantasy: The Accuracy of the Vegas Lines in MLB

Bales-Fantasy-Baseball-Cover-3DThis is an excerpt from Jonathan Bales’ newest book Fantasy Baseball for Smart People: How to Profit Big During MLB Season — a tutorial for making money playing Daily Fantasy Baseball.

For Daily Fantasy Baseball players, the value of the Vegas lines really comes down to one question: can the Vegas lines help us make more accurate predictions? And that answer, without a doubt, is yes. We have the best oddsmakers in the world weighing weather, ballpark factors, pitcher matchups, recent performance, and lots of other factors. When they predict that the Cowboys will score 24 points or that the Rangers’ median projection is five runs, that’s highly likely to be very close to reality. There’s all sorts of data that I’ve collected in various sports showing how accurate Vegas has been.

Even if you consider what Vegas offers to be “common sense”—an argument I’ve heard from a number of people who somehow have decided to forgo leveraging their apparent ability to beat Vegas into huge profits—there’s no doubt that we can increase our efficiency by stealing Vegas’s predictions.

I liken this to a company outsourcing work that they can get completed cheaply and more efficiently than what they could do on their own. So why in the world would you run through all of the work of considering 100 different inputs that might affect a baseball team’s run projection when you can get that information immediately from a highly reliable source? Even if you were just as accurate — and you likely aren’t — it still wouldn’t make sense to not take that sort of data for free. The cost — a couple minutes of your time — is basically nothing, yet you can receive all sorts of incredibly useful insights.

At this point, I think it’s important to confirm that Vegas is not only accurate, but also a reliable tool for Daily Fantasy players. So I looked at the overall Fantasy production for teams in games projected at eight runs, then compared that to other run totals.


There’s a very clear, linear relationship here; games projected at six runs by Vegas have historically seen between 20 and 30 percent fewer Fantasy points than those projected at eight runs — depending on if we use the opening or closing line. On the other end of the spectrum, games projected at 10.5 runs have witnessed around 33 percent more Fantasy points than those projected at eight runs. Those are pretty sizable differences, eh?

I also charted the reliability of using the Vegas lines as a direct proxy for Fantasy scoring. Here’s a look at how the change in run total has historically compared to the change in Fantasy production.


Up until the 9.5-run mark, Fantasy production has been directly linked to the Vegas lines — an almost perfectly linear correlation. What’s really interesting is that actual Fantasy production jumps considerably over what we’d expect once hitting the projected 10-run mark, i.e. if you targeted teams in games projected at 10 or more runs, you would have seen a sizable jump in Fantasy production over games at just 0.5 fewer projected runs.

I’m not entirely sure why this is the case. It could just be that teams with really high projected run totals also have far more upside than others. Maybe 10.5 runs is the median projection for a specific game, but the high-upside offenses in that sort of contest have the ability to occasionally erupt for 20-run sorts of contests that throw off the overall numbers. It could also be that Vegas just doesn’t want to offer totals that are perceived as “too high.”

Either way, two things are true:

  1. We can trust the Vegas lines to help project players in Daily Fantasy Baseball.
  2. When possible, we should target hitters in games with a high projected total.

Like this analysis? You can download Jonathan’s book “A Guide to Winning at Daily Fantasy Sports” for free right here. You can also get his 2015 Daily Fantasy Baseball Package for free by signing up and depositing at DraftKings.

Thanks to Jonathan Bales for this excerpt!

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Jonathan Bales

Jonathan Bales is the author of the Fantasy Sports for Smart People book series and a DraftKings Pro. You can reach him on Twitter @BalesFootball.
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