MLB Gambling Trends; Focus on the Over/Under and Home-Field Advantage
Before we jump into the trends and facts, a little bit about the data that was used for this analysis. Regarding the over/under lines and game results, data was scraped was Covers.com. Game results over the past seven years (2009 - 2016) were scraped to make the following conclusions and analysis. Regarding the baseball statistics, data was taken from FanGraphs.com, an extremely reliable and extensive baseball database. In order to form accurate predictions and analysis, games from the month of April were entirely removed from the dataset. Being the first month of the baseball season, April is when teams begin to form trends. I did not want a couple good or bad performance games in April to act like outliers and skew the data in one direction. Lastly, only regular season games were taken into consideration. In total, 12,878 games were included in the dataset.
One topic I sought to investigate were the monthly trends in statistics and gambling scenarios. Are more home runs going to get hit during the summer months? Or are more home runs going to be hit in September and October when the baseball may be more susceptible to carry further in the thinner air. Below are the seasonal changes in pitching stats across the entire league for each month.
Looking at the HR/9, which measures the number of Home Runs a pitcher allows per 9 innings, there is a slight seasonal increase come September and October. While there are significantly less games played in October and therefore less data to analyze, the increase still suggests a climate impact on Home Runs. A similar statistical change can be seen in WHIP (Walks & Hits per Inning Pitched), suggesting a pitcher on average allows more base runners in May, June, September, and October versus July and August. Now lets take a look at batting statistics
As batting statistics are going to represent the inverse of the pitching statistics, there in no surprise that the slugging percentage increases in September and October when pitching HR/9 increases as well. On base percentage and batting average stay fairly consistent throughout the season.
Now lets shift gears to the gambling scenarios. First we will take a look at home-field advantage. The below visualization displays the top ten teams who have showcased the largest margin in home field advantage, shown in percentage of home games each team has won.
Before moving forward, it is important to note the statistical significance in a minor percentage difference. Although the Yankees only winning 59% of their home games might not seem like a significant advantage, when it comes to gambling and a substantial amount of money is at stake, each percentage point matters. If I were to have bet on the Yankees in every single one of their home games from 2009–2016, I would be on my private yacht right as it leads me to my private island where my private jet awaits to take me to my next destination.
Continuing to investigate the home stadiums, below is a picture depicting the largest differences in games hitting the over versus games hitting the under within each ballpark. The image contains the top five statistical differences.
Out of the top 5 differences, Colorado’s stadium is the only field where the over is hit more often. You may think this is an obvious stat, as Denver being in higher altitude, more home runs are going to be hit, undoubtedly the over is going to be covered more often. However, wouldn’t Vegas take this into consideration when setting the Over/Under totals?
Conversely, 57% of games played in Wrigley Field (the Cubs home stadium) hit the under. Atlanta, Tampa Bay, and Seattle all showcase significant differences as well, with a majority of games hitting the under.
Finally, a breakdown of the percentage of games hitting the over or under over the course of each month.
As mentioned earlier, while there are less regular season games played in the month of October, the 20% statistical difference can be quite telling. The Over trumps the Under in every month except for July and October.
There are numerous factors that play a role in setting the Over/Under totals and the spreads for each game. And as even the casual gamblers are aware, the spreads shift up until game time depending on which side a majority of the bettors are favoring. This is so Vegas or the House will assure themselves a profit regardless of the outcome. That being said, the educated gambler can prey and exploit the uninformed, casual gambler. With a great subject matter knowledge, and placing your bets at the right time, an educated gambler can make a killing. This blog simply serves as another resource for the educated gambler.
