Betting on baseball can be a tricky game. Compared to most other sports, baseball has A TON of randomness to it. Does a fly ball lead to a 388-foot pop-out or a 390-foot home run? Does a line drive hit at a magnificent 105 MPH find the gap or is it directly at the second baseman?
This randomness is why baseball prizes its long season, nearly double the number of games of the NBA and NHL. Any baseball game
can be won by any team. However, over the extremely long grind of 162 games, the better teams will slowly but surely rise to the top allowing the law of large numbers to work its’ magic.
A reasonable reaction to the premise that any team can win any baseball game is to ask; is that accurate, or is it bull**it? To start to examine this, a great place to start is to look at what the sportsbooks think.
In all of the 2021 MLB season, only 5 games had a team with larger payouts than 3-1 and only 230 games (about 9%) had a team with a higher payout than 2-1. Compare this to an NFL Sunday and the difference is clear. In Week 1 of the 2022 NFL season, 4 teams had odds higher than 2-1, comprising 25% of games, almost 300% more than the 9% of MLB games that had a team with odds this long! Underdogs in baseball are consistently given lower payouts because the sportsbooks believe they have a real shot in any given game.
To sum, although people think “Any given Sunday” a
ny NFL team can win, truly the underdogs in baseball are the ones with a real chance.
Given that all baseball games are always within reach by any team, how should one look to bet on MLB games?
Just like in baseball where the law of large numbers will allow the Astros to separate from the Athletics, so too over many bets placed with positive expected value we can build a successful process.
To do this, we will look for patterns that should provide value over the long run. In this series, we will one by one analyze a large variety of trends to find where to pinpoint value. These will include home and away, over-under bets, right vs. left-handed pitchers, predictability of starting pitchers, and more to find the most predictive patterns.
Analysis #1 – Home and Away
In sports, home field has traditionally provided a genuine advantage and in baseball, this has been incredibly consistent. Since the 1950s, the variation in home winning percentage per decade only ranged from .535 to .542. Any individual year could provide a slightly more moderate swing, but home winning percentage has stayed in the range of 52% to 56% over half a century.
There are some clear advantages to home field in baseball. The two clearest advantages are the dimensions of the playing field and “last licks”. Because baseball fields vary greatly, a General Manager will build their team partially around their playing field. Classic examples are the Yankees seeking power hitting left-handers to take advantage of the short 314-foot right field porch, or the Colorado Rockies looking for ground ball pitchers, since routine pop-ups can go yard through the thin air at Coors Field.
The less obvious and more scrutinized potential advantage is the umpire’s calls, specifically balls, and strikes. Several studies have found that the home team gets around 1 to 2 percent more calls at the plate when the batter doesn’t swing.
Regardless of why they have an advantage, for our purposes the important question is simple, the home team has a slight advantage, but do the odds properly incorporate this, do they overestimate it?
In 2021, 59.3% of home teams were favored to win (excluding ‘pick em’ games). This is a higher percentage of games than home teams have ever won in the past century. One might then assume that they should simply bet on the away team and take the winnings. However, betting on the away team in every game in 2021 would have led to huge losses.
If home teams are overvalued and betting on the away teams still loses money, where is there value?
The answer lies in a subset of games, heavy home underdogs.
Out of 2462 games in 2021, 230 of them had home underdogs with money lines +150 or higher. On average these money line bets produced a profit of 8.14%. Further, when the line was as high as +200, the average profit was 16.8%.
To take this a step further, we filtered to see if there was a difference when the games were predicted to be high or low scoring.
Among games that had an over-under total of 7.5 or less, heavy (150+) home underdogs produced an outstanding return of 50.4%.
One hypothesis to explain this is a variation of an idea you are likely to see repeated on this site. The higher scoring the game, the greater the chance the better team will win. Essentially, the smaller the sample size, the better chance of an unexpected result happening.
Consequently, when games are lower scoring, there is a greater chance of a “random” or chance outcome occurring, since one hit, error, or slight gust of wind can swing the outcome.
Likely, most heavy home underdogs are bad teams whom the public is inclined to bet against. Consequently, their inherent home-field advantage is ignored, as bias against these bad teams incorrectly reassures bettors’ that these inferior teams will not be able to take advantage of their home field.
The high payouts for these games, combined with the relatively higher likelihood of an underdog pulling a “chance” victory, leads to value over time for savvy bettors.