How Efficient Is The MLB Betting Market?
First inning betting markets have become extremely popular in recent years. Sportsbooks now offer wagers such as:
- NRFI (No Run First Inning) - YRFI (Yes Run First Inning)
These bets depend entirely on whether either team scores in the opening inning.
To understand how these markets perform long term, we analyzed every MLB game since 2004.
The dataset contains 52,697 games.
How Often Is There A Run In The First Inning?
Across the entire sample:
Games with at least one run scored in the first inning: 26,953 Percentage of games: 51.14%
That means slightly more than half of MLB games see a run scored in the first inning.
How Often Does Exactly One Run Score?
Many first innings produce only a single run rather than a big rally.
Games with exactly one run in the first inning: 11,797 Percentage of games: 22.38%
So roughly one out of every five MLB games starts with exactly one run scored.
How Often Does No One Score In The First Inning?
The opposite scenario — a scoreless opening frame — is almost just as common.
Games with no run scored in the first inning: 25,744 Percentage of games: 48.85%
This means NRFI outcomes occur in just under half of all MLB games.
Home Team First Inning Scoring Results
Because the home team always bats second, they sometimes benefit from knowing whether the visiting team scored earlier in the inning.
Historical results show the home team scores more frequently than the road team.
Home team scores in the first inning Record: 11,225 – 5,619 Win rate: 66.6%
However, betting blindly on this trend historically produces negative returns because sportsbooks adjust odds accordingly.
Away Team First Inning Scoring Results
The visiting team bats first, giving them the first opportunity to score.
Away team scores in the first inning Record: 8,846 – 5,980 Win rate: 59.7%
Despite solid win rates, betting these outcomes blindly also results in negative long-term returns due to sportsbook pricing.
What This Means For NRFI / YRFI Betting
The overall scoring distribution shows that first inning outcomes are very close to a coin flip.
Key observations:
- YRFI occurs in about 51% of games - NRFI occurs in about 49% of games - First inning scoring is extremely balanced over long samples
Because the probabilities are so close, the sportsbook’s vig becomes a major factor when betting NRFI or YRFI markets.
Key Takeaways
From over 52,000 MLB games since 2004:
- 51.14% of games feature at least one first-inning run - 48.85% of games have no first-inning runs - 22.38% of games have exactly one run scored in the first inning
The near 50/50 distribution shows that first inning betting markets are relatively efficient over long samples.
Related Reading:
This article should link to your other MLB research pages:
- MLB Betting Market Analysis Since 2004 https://www.procomputergambler.com/mlb-betting-market-analysis-since-2004/ - MLB One-Run Game Betting Trends - Are MLB Underdogs Profitable? - MLB Betting Market Efficiency Study
FAQ
What percentage of MLB games have a run in the first inning?
About 51% of MLB games have at least one run scored in the first inning based on historical data since 2004.
How often does NRFI win?
NRFI (No Run First Inning) occurs in roughly 49% of MLB games.
Is NRFI or YRFI better to bet?
Because outcomes are close to 50/50, profitability usually depends on identifying pitching matchups and situational edges rather than betting blindly.
