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Calculating Win Percentages for the 2019 MLB Season

Calculating Win Percentages for the 2019 MLB Season.

Being that it's been done time and time again, we here at SPORTSSOTROS wanted to chime in and give our take in using the beautiful discipline, that is, Mathematics, in calculating the numbers to give us a clearer view of teams' performances. Due to the worldwide shutdown over the pandemic, as the MLB ceased operations, they plan to continue under a 60-game season this coming July 25, 2020. While that's going on, we'd thought to look back at the 2019 season, played in full, and check out the stats.

Famous Greek mathematician Pythagoras laid down his equation in finding the area of a right triangle a2 + b2 = c2 known as the Pythagorean Theorem. Baseball Mathematician named Bill James have implemented a rather similar theorem with the following equation:

$$predicted \ wins \ percentage = {runs \ scored^2 \over {runs \ scored^2 + runs \ allowed^2}}$$

(predicted wins percentage means the estimated percentage of games won often written as a 0.000 decimal format.

runs scored2 means the team's runs scored, squared.

runs allowed2 means the team's runs allowed, squared.)

As you've learned in Arithmetic/Algebra, an equation presenting its variables simply just needs numbers to be plugged in to. Since I'm personally based in Los Angeles, CA, let's sample this calculation with the LA Dodgers.

Stats in 2019 tell us, during the regular season, the LA Dodgers had an RS (runs scored) of 886, and had an RA (runs allowed) of 613. When we plug in these numbers into the equation, we have the following:

$${886^2 \over {886^2 + 613^2}} = 0.676$$

(Remember to round the final answer to the thousandth place, which is the third number to the right of the decimal point.)

Thus, the LA Dodgers have an estimated 0.676 or 67.6% wins for the 2019 season. How does this compare to the percentage of the games the Dodgers actually won? Let's take a look:

Out of a full 162-game season, with no game cancellations, the Dodgers won 106 out of 162 games (ranked #2 in the overall standings and ranked #1 in the National League West Division). If we divide the Dodgers' wins by the overall games scheduled for the season, we get:

$${106 \over {162}} = 0.654$$

Interesting. Judging from the Baseball Pythagorean Theorem, we subtract both answers to see how much we were off by—known as an error in predicting the win percentage. For that, we simply subtract the actual winning percentage minus the predicted percentage. We get:

$${0.654 - 0.676} = -0.022$$

What this -0.022 means is that the Dodgers won fewer games than originally predicted; If you get a positive answer, it means the team won more games than originally predicted.

Going through all 30 teams on this article alone would be a lot to go through, so I decided to use the popular, open-source program LibreOffice Calc spreadsheet software. Going through all 30 teams' calculations, here are the results:

Spreadsheet for calculating win percentages in the 2019 MLB season.
Feel free to download our whole spreadsheet here. Created and made using LibreOffice Calc.

If you look at the sheet carefully, you'll see that both the Brewers and the Cubs have a significant gap—Brewers winning more than expected and the Cubs losing more than expected. Even though the Brewers "brewed" through nicely during the post-season, they were a dollar short of missing the World Series. Close but no cigar.

What does this tell us overall? Known as sabermetrics, the art of implementing Math into baseball, the accuracy isn't completely on the dot, but it does give us a forecast of how a team is doing. Just a reminder: These calculations were done during the regular season, and may or may not reflect the best odds of who are likely to win the championship. Is there a mathematical formula for that? We'll dive more into this as our research continues.

Oh, and for those who are still fearful and disgusted by Math, remember this: Math is like cooking, and all you need to do is follow the recipe. Like any other discipline or hobby, practice makes perfect. You can do this!

This article was sponsored by The Seeds of Math. We WILL NOT provided any secret winning formulas and WILL NOT work with personal, illegal bookies looking to use our research to compose a sports betting model in exchange for money. As of current, we are not affiliated with any sports entity whatsoever and are provided this for extensive fanaticism of sports and informational reasons. In part with adding such techniques to our portfolio, we won't be responsible nor held accountable if such mathematical formulas give the bettor(s) a losing streak. It is encouraged that you gamble responsibly and legally, as any tout or accusations toward our current mathematical research will not be dealt with. Under the KCU Network, we are here to educate and entertain, and will not agree to exchange monetary "juice" for a secret winning math formula, kept under the rugs, to circumvent regulations by the federal government and sports books around the US and the world. Not once do we force our fans and readers to gamble and use any techniques provided, and so any disagreements with this disclaimer is free to detach from our platform, as any legal action taken against us will not be carried further. For more on this topic of discussion, please contact us.

Runs Scored and Runs Allowed stats courtesy of and ESPN. Also, a big thank you to MathJax for the nicely-rendered equations!

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