Stat Glossary
EV
Exit Velocity (mph) — How hard the batter hits the ball on contact, measured by Statcast radar.
The single strongest predictor of HR potential. Elite HR hitters average 90+ mph; league average is ~83.5 mph.
Displayed as a trailing average of all batted balls.
LA
Launch Angle (degrees) — The vertical angle of the ball off the bat.
Home runs typically require 25–35°. A high average LA indicates the batter elevates the ball consistently.
The model uses a trailing average; extreme groundball or popup hitters score poorly here.
BBL%
Barrel Rate — Percentage of batted balls classified as “barrels” by Statcast:
98+ mph exit velocity at an optimal launch angle (roughly 25–35° at 98 mph, widening as EV increases).
The model's strongest single feature. Elite: 12%+, League average: ~6.5%.
HH%
Hard Hit Rate — Percentage of batted balls hit at 95+ mph exit velocity.
A broad power indicator. The model weights this less than BBL% since hard-hit grounders don't go for HRs.
League average: ~36%.
FB%
Fly Ball Rate — Percentage of batted balls classified as fly balls (launch angle 25°+).
A high FB% is necessary but not sufficient for HR production — the ball also needs to be hit hard.
The model weights this negatively in isolation since soft fly balls and popups suppress HR rate.
Complements HHFB%. League average: ~9.5% (per batted ball).
HHFB%
Hard Hit Fly Ball Rate — Percentage of batted balls that are both hit at 95+ mph
exit velocity and classified as fly balls. This is the most direct Statcast proxy for home run potential
— a hard-hit fly ball is the fundamental precursor to a HR. Elite HR hitters typically post 10%+ HHFB.
League average: ~4.5%.
PF
Park Factor — Multiplier reflecting how HR-friendly the game's venue is.
Values above 1.0 boost a batter's probability; below 1.0 suppress it.
Coors Field (1.35) is the most extreme hitter's park; Oracle Park SF (0.93) the most extreme pitcher's park.
The model also applies handedness-specific adjustments: LHH get a +0.05 boost at Yankee Stadium (short RF porch),
while RHH get suppression at Comerica Park (deep LC). These are deltas on top of the base park factor.
SLG
Slugging Percentage — Current season SLG for this batter. Shown as context; not a direct model input
but correlates with overall power production. A high SLG alongside elite barrel rate is a strong combined signal.
vs R/L
Platoon SLG — The batter's slugging percentage specifically against right-handed
or left-handed pitchers this season, depending on the pitcher they face today.
Most batters have significant platoon splits; a LHH facing a RHP (favorable) will show their vs-R SLG.
H/A
Home/Away SLG Split — The batter's slugging percentage at home (HM) or away (AW)
this season, depending on where today's game is played. Some hitters perform significantly better
in their home park due to familiarity with dimensions and conditions. Requires 10+ PA to display.
IBB
Intentional Walks (last 14 days) — Number of intentional walks over the past 14 days
relative to total plate appearances. Shown in amber when non-zero. A high IBB rate signals that opposing teams
are actively avoiding this hitter — a badge of respect for their power, though it also means fewer
opportunities to swing.
H2H
Head-to-Head — Career stats for this batter vs this specific pitcher.
Shows HR count and plate appearances (e.g. 2HR/15PA). Requires 5+ PA to display.
A strong H2H record adds confidence; 0HR over many PA is a mild negative signal.
Small samples should be interpreted cautiously.
Pitcher Metrics
P.HR%
Pitcher HR Rate — The pitcher's home run rate per plate appearance this season
(displayed as HR/PA%). Higher values indicate a more HR-prone pitcher. League average is ~3%.
Sourced from MLB Stats API (season HR/IP). Barrel%/HH% allowed use current-season Statcast where available, falling back to league average for pitchers with insufficient sample.
A key model feature — the third strongest predictor after barrel rate and exit velocity.
P.BB%
Pitcher Barrel Rate Allowed — Percentage of batted balls against this pitcher
classified as barrels. A high P.BB% indicates a pitcher who struggles to prevent hard, well-struck contact.
Sourced from current-season Statcast (refreshed monthly), falling back to league average (~6.5%) for pitchers without enough tracked batted balls yet.
P.HH%
Pitcher Hard Hit Rate Allowed — Percentage of batted balls against this pitcher
hit at 95+ mph. A high P.HH% indicates a pitcher who struggles to generate weak contact.
League average: ~36%. Higher = more favorable for the batter.
Zone & Matchup
Matchup Score
Zone + Pitch Type Matchup Score (0–100) — A composite score measuring how dangerous
today's pitcher matchup is for this batter, based on two components:
Zone Score (70% weight) — How often the pitcher throws into this batter's HR hot zones
in the strike zone. Computed from Statcast pitch locations (2025–2026). High = pitcher works into power zones.
Pitch Type Score (30% weight) — Overlap between the batter's HR pitch type profile
(what pitches they hit for HRs) and the pitcher's pitch mix. E.g. if a batter hits 50% of HRs off fastballs
and the pitcher throws 40% fastballs, that's high overlap.
Scores 65+ show “⚡ HOT MATCH”, 35–64 show “△ WATCH”.
Badge System
⚡ HOT ZONE
Hot Zone Match — The pitcher's combined zone + pitch type matchup score is 70 or above.
Indicates the pitcher frequently throws into this batter's HR hot zones at a high rate.
The strongest zone signal — red pulsing badge on pick cards.
🎯 BULLSEYE
Peak Zone Alignment — The batter's single highest HR-producing zone in the strike zone
matches the pitcher's single highest HR-allowed zone. Both peaks must have a normalized score of 50+
to qualify. Shown as green crosshairs on both heatmaps in the zone modal.
🎯 TRIPLE
Bullseye + Pitcher Frequency — All conditions for BULLSEYE are met, plus the pitcher
also throws to that same zone at 50%+ of their maximum zone frequency. The strongest individual zone signal:
batter hits HRs there, pitcher allows HRs there, and pitcher actively throws there.
Green glowing badge on pick cards.
🚀 HITTER'S PARK
Hitter's Park — The game is being played at a venue with a park factor of 1.10 or above,
meaning the park meaningfully boosts HR probability. Examples: Coors Field (1.35), Great American Ball Park (1.22),
Fenway Park (1.15). The model applies this as an additive boost to the base probability.
Orange rocket badge.
☁ FB PITCHER
Fly Ball Pitcher — The opposing pitcher has a fly ball rate of 32%+ on balls in play.
Fly ball pitchers surrender more HRs than ground ball pitchers since elevated contact more frequently
leaves the yard. A mild positive signal for all batters in the matchup. Blue badge.
⛰ GB PITCHER
Ground Ball Pitcher — The opposing pitcher has a ground ball rate of 50%+.
Ground ball pitchers suppress HRs by keeping the ball down. A mild negative signal.
Brown badge. The model applies a probability cap for extreme GB pitchers.
★ CONSENSUS
Consensus Pick — This player appears in 3 or more external HR prediction sources
(Covers, RotoWire, SBR, SI.com, etc.) scraped daily. A green star badge indicates broad agreement
between the model and external analysts. Grey star = 2 sources.
🔥 HOT FORM
Hot Form — The batter's recent 14-day barrel rate is significantly above
their career rolling average (4%+ above). Indicates the batter is in an elevated contact quality streak.
Amber fire badge.
❄ COLD FORM
Cold Form — The batter's recent 14-day barrel rate is significantly below
their career rolling average (4%+ below), or they have hit 0 HRs in 10+ consecutive games (HR drought penalty).
Blue snowflake badge. The model applies a score reduction for extended droughts.
❄ STREAK
Miss Streak — Number of consecutive days this player appeared in the top 5 picks
without hitting a HR. Shown as a cold badge on pick cards. Resets when the player hits a HR or
leaves the top 5. Used as a caution signal for extended cold streaks in the top 5.
CONF: HIGH
AI Confidence Tier — Groq AI rates each top 5 pick as High, Medium, or Low confidence
based on how many independent signals align beyond the raw model score.
High = 4+ strong signals (EV, barrel%, form, park factor, pitcher vulnerability all pointing the same direction).
Medium = 2–3 signals. Low = 1 signal or conflicting signals. Shown as a small badge on the player name.
A/B/C/D GRADE
Pitcher Matchup Grade — Groq AI assigns a letter grade to each pitcher matchup based on
how favorable it is for hitting a home run today.
A — Very favorable: hittable pitcher, elevated HR rate, weak contact suppression.
B — Favorable: above-average HR vulnerability, some exploitable tendencies.
C — Neutral: average HR risk, no strong edge either way.
D — Tough: low HR rate, strong contact suppression, difficult matchup.
Grade appears as a small letter badge next to the pitcher name on each pick card.
Based on pitcher HR rate, barrel% allowed, hard hit% allowed, and park factor.
Model & Scoring
Score
Power Score (1–100) — The model's HR probability mapped to a 1–100 scale
for display purposes. Not a percentage — it's a relative ranking tool. Higher = model rates this
batter more likely to hit a HR today vs the field.
🔥 ❄
Form Flags — Based on recent 14-day Statcast data vs career rolling average.
🔥 Hot: recent barrel rate or HHFB% significantly above career average.
❄ Cold: recent metrics significantly below career average.
The model blends career (60%) and recent (40%) stats, so form flags indicate a meaningful current divergence.
TOP 5
Today's Top 5 Picks — The five highest-ranked candidates by raw HR probability,
straight ranked with no diversity filter. If the model genuinely likes 3 hitters in the same game,
all 3 can appear in the Top 5.
Accuracy tracking applies only to these 5 picks.
★ CONSENSUS
Consensus Pick — This player appears as a home run pick from 2 or more independent
sportsbook/media sources (DraftKings, FanDuel, RotoBaller, BettingPros, Covers, SBR, Dimers, and others),
scraped and aggregated daily. Historically the single strongest badge on the dashboard at a 30% hit rate
(vs. ~20% baseline for Top 5 picks), though sample size is still small.
Barrel Δ
Barrel Trend — The change in this batter's barrel rate over the last 14 days
vs. the 14 days before that (e.g. +6.0 means barrel rate climbed 6 points). Captures momentum that a flat
recent-form average misses — a batter trending up looks different from one who has been flat,
even if their current barrel rate is identical. Experimental: applied as a small probability nudge,
not yet a trained model feature. Being validated against actual results.
Pitch Fit
Pitch-Arsenal Matchup Score — A 0-100 score measuring how much this batter's
home-run-by-pitch-type tendencies (e.g. mashes sliders) overlap with what this specific pitcher actually
throws (e.g. throws 35% sliders). Built from 3 seasons of Statcast pitch-type data. Higher scores indicate
a batter facing a pitcher who throws the pitch types that batter historically hits for power.
Experimental: applied as a small probability nudge, not yet a trained model feature.
Weather
Temperature & Wind — Game-time temperature and wind conditions fetched
from Open-Meteo for each park. Temperature below 50°F suppresses HR probability slightly;
above 75°F adds a small boost. Wind direction is now used directly: the actual compass bearing
toward center field for each park is compared against the real wind direction to compute a
tailwind (boost) or headwind (penalty) component. A 15 mph direct tailwind at Wrigley (south wind)
adds ~+1.1% HR probability; a direct headwind subtracts the same. Crosswinds near 90° are
neutral. The ↑/↓ arrow on pick cards indicates a meaningful weather adjustment.