gERA: A Predictive Metric for Pitching Performance
Each pitcher in our system is assigned a preseason projection of gERA (“guru” ERA), a predictive form of ERA. ERA (earned run average) is a traditional pitching statistic that tells you how many earned runs a pitcher has given up per nine innings pitched. However, ERA is a backward-looking statistic that tells you what has already happened, rather than what's likely to happen in the future. That's where gERA comes in. By using advanced pitching stats like FIP (fielding independent pitching), K:BB ratio, and wOBA allowed, we're able to develop a predictive metric for how well a pitcher is likely to perform in future games. Additionally, since we are evaluating each player individually, we can also look at each team’s staff of relief pitchers and obtain a comprehensive bullpen gERA for every team.
gWRC+: A Predictive Metric for Hitting Performance
Just as we use gERA to predict how many runs a pitcher is likely to give up, we use gWRC+ (“guru” WRC+) to predict how many runs a hitter is likely to generate. WRC+ (weighted runs created plus) is a statistic that measures a hitter's ability to generate runs relative to the league average. Our version, gWRC+, is designed specifically to be predictive of future performance. By assigning each hitter a preseason projection of gWRC+, and then iterating that number based on performance in predictive indicators, we can determine how many runs each player is worth when they're included in the starting lineup. This is especially helpful when star players have off days, as our system can quantify how much their absence will affect the team's overall run production.
Additional Factors That Affect Baseball Scores
Of course, baseball is a complex sport, and there are many other factors that can affect how many runs each team scores. Our system takes into account variables such as altitude, temperature, and wind speed and direction to get the final gameday projection. For example, a game at Coors Field in Denver (which has a high altitude) is likely to have more runs scored than a game at Citi Field in New York (which has a much lower altitude). By combining these additional factors with our predictive run projections based on gERA and gWRC+, we're able to generate win percentages as well as projected totals.
At Gameday Guru, we are continuously improving and refining our MLB projection system. We are always looking for new and innovative ways to incorporate data and analytics into our system, to give our users the most accurate and up-to-date information possible. Our goal is to provide baseball fans with a comprehensive view of each game, and to help them make informed decisions when placing bets or drafting players for their fantasy teams.