How the MLB HR Power Score Works
The HR Power Score is a single number from 0 to 100 that ranks every batter on tonight's MLB slate by how good a home run spot they are in. A score near 100 means the batter, the pitcher, the park, and the weather all line up in the hitter's favor. A score near 0 means the opposite. It is a descriptive rating, not a probability and not a graded win-loss pick. This guide explains exactly what goes into it and how to read it.
You can see today's ranked list on the MLB home run picks page, or the full board with every breakdown at hr.openinglineanalytics.com.
The four inputs
Every score is built from four parts. Each part is scored on its own, then blended together with the weights below. The weights reflect how much each factor actually moves home run outcomes.
1. Batter power — 40%
The biggest driver. This looks at how often the batter hits home runs per plate appearance, plus the quality of contact behind it: barrel rate and hard-hit rate from Statcast. It also folds in the last 15 days of form so a hitter who is locked in gets credit, and it uses the batter's split against the handedness of tonight's starter.
2. Opposing pitcher — 25%
How home-run-prone the starter is. This uses home runs allowed per nine innings, barrel rate and fly-ball rate allowed, and the pitcher's home run rate against batters of this hitter's handedness. A fly-ball pitcher who gives up loud contact pushes the score up.
3. Park — 20%
Ballparks are not equal for home runs, and they are not equal for lefties and righties. This uses three-year home run park factors from Baseball Savant, split by batter handedness. A left-handed pull hitter at Yankee Stadium gets a very different park score than the same hitter at a pitcher-friendly yard. Note that the famous Coors Field effect is mostly about doubles and runs, so its home-run-specific park factor is more modest than most people expect.
4. Weather — 15%
Warm air and a wind blowing out carry the ball farther. This starts from a neutral baseline and adjusts for temperature, then for wind speed projected onto the direction of center field at that specific park, plus a small humidity effect. Domes and closed roofs are treated as neutral because weather does not apply.
Why the score is ranked, not absolute
After the four parts are blended into a raw number, every batter is ranked against the rest of tonight's slate to produce the final 0 to 100 score. That is important: the score is relative to the games being played today. A 90 means this batter is in one of the best spots on tonight's board, not that they have a 90% chance to homer. On a slate full of hitter friendly parks and warm weather, the bar to reach a high score is higher.
How to use it
- Treat it as a shortlist. The top of the board is where the batter, pitcher, park, and weather all agree. That is the natural place to start research, not the finish line.
- Read the breakdown. Two batters can share a score for very different reasons. One might be elite power in a neutral spot, another might be average power in a perfect park with the wind out. The full board shows each component.
- Compare it to the price. A high score on a batter the market has already made expensive is less useful than a high score the odds have not caught up to yet.
- Remember the variance. Home runs are rare events. Even the best spot on the board is still a long shot on any single night. The score tells you who is in a good spot, not who is going to go deep.
Where the data comes from
Batter and pitcher profiles come from Statcast, refreshed daily. Park factors are three-year rolling home run factors from Baseball Savant, split by handedness. Weather comes from an hourly forecast for each ballpark, and the wind is projected onto the real center-field bearing of each park. Lineups come from the MLB Stats API, so scores firm up once a team confirms its order.
See tonight's home run board
Every batter on today's slate, ranked by HR Power Score and updated daily. Free.