April 26th, 2023 – MLB Daily Betting Card

• Wednesday April 26th’s MLB Betting Card features 8 games for a total of 25 units bet with a max payout of 46.23 units.

• Yesterday’s 4/25/23 Card was a brutal day with a loss of -20.02 Units on a 3-8 record.
  • A walk off 2 run HR by the Giants salvaged 7.81 units at the end of the night

• The full season 2023 MLB Betting Results is now at a Net Profit of +45.23 Units with a 6.7% ROI.

After the shellacking that I was given early in yesterday’s card I had plenty of time to review the model and identify any leaks responsible for the damage. I made a few changes to the Model as a result. See under today’s card the changes that were made.

*Final Results

Glossary of terms:

• WP% = Win Probability %
  • This is the key to my model, I source these typically from Fangraphs as they do a pretty accurate job based on backtesting of past data. I also add my own adjustments to make them more accurate. The data as a whole is accurate, but at a team level it has some variation. My adjustment adds or subtracts to the WP based on winning records of teams playing.
• ML Odds = The Moneyline odds that the sportsbook is offering for the bet
• BE ML = Breakeven Moneyline
  • This is a calculation to convert the Moneyline into a percentage format to highlight how often the bet would have to win to show a breakeven in money won/loss on a bet with the given odds.
• eROI = expected Return on Investment
  • This is the expected Return on Investment a bet would return overtime if we were able to consistently place a similar bet. The formula is WP/BE ML.
  • For example a bet with an eROI of 10% would be expected to show a net profit of 10% over the true odds. If a bet had a WP = 50%, meaning it would win half the time, we would expect to show a profit of 10% on our bets if we won 5 and lost 5.
• Base and Edge = are terms I’m using to determine the appropriate unit amount to bet
  • Base = (WP%-40%)/5%. It is rounded down to each whole interval so that only bets with WP 45% or greater will be eligible for a bet.
  • Edge= awards a bonus unit if eROI/10% > 1

Model 4.2:

Risk management was the key change desired in the model update today. One of the early contributors to yesterday’s losses was a 6 unit play on the NYM that I was originally on the fence about playing due to unknown pitcher starter. In addition there was the 4 unit Oakland play still pending at the end of the night that I knew had a low chance at hitting due to its 48% WP.

• I changed the model to reduce the number of large unit plays by only limiting an award of 1 unit per edge over 10%, previously it was 1 every 5% difference between ML BE and WP . I also adjusted the Base Units calculation to not add an extra unit when an edge was over 5% between ML BE and WP on a bet. These unit additions were making plays with larger edges too risky as bet sizes were often reaching the 6-8 unit range each day. That is too large of a variation from the base unit of 1.

• One last change that will hopefully improve the accuracy of the WP% was that I changed my WP% adjustment from being a full season record Win/Loss ranking review for a team, but instead only looking at last 14 days of performance.

• In almost every sport there is a large correlation between recent form and forward performance. Some teams start out cold and then catch on fire and possibly fall back down. 14 days seems a reasonable amount of time to account for enough variance in what may have been a tough series matchup or two and not penalize a team for a weak slump to start the season.

Here’s to hoping that 4/25/23 remains the worst day of the season and these changes allow us to mitigate risk and continue to churn out strong profitable days going forward.