MLB One-Run Games: 28.4% Finish by Exactly One Run

Quick Answer: How Often Are MLB Games Decided by One Run?

In the ProComputerGambler historical dataset beginning in 2004, 14,968 of 52,697 MLB games were decided by exactly one run — 28.4% of all games analyzed. That makes one-run finishes common enough to matter when comparing a moneyline with the standard -1.5/+1.5 runline.

One-Run Game Metric	Historical Result
Total MLB games analyzed	52,697
Games decided by exactly one run	14,968
One-run game percentage	28.4%

This is primarily a run-distribution statistic, not a standalone betting system. You do not know before first pitch whether a game will finish by one run, so retrospective one-run results are most useful for understanding market structure and the importance of runline pricing.

Dataset and Methodology

This study uses ProComputerGambler’s historical MLB database beginning in 2004. The overall sample contains 52,697 games, with final score margin used to identify games decided by exactly one run. Betting-price results shown below describe subsets of those completed games. They are historical observations, not a claim that the same outcome distribution must persist in future seasons.

For broader context on favorites, underdogs, home teams, totals, and runline outcomes, see our MLB betting trends since 2004 market analysis.

MLB One-Run Game Frequency Since 2004

Across the 52,697-game sample, 14,968 games ended with a margin of exactly one run. Dividing 14,968 by 52,697 produces the 28.4% historical rate.

Put differently, more than one out of every four games in this dataset finished with the winning team ahead by only one run. That matters because the difference between winning by one and winning by two is exactly what separates a standard favorite moneyline win from a -1.5 runline cover.

How Favorites Performed in One-Run Games

The historical favorite subset produced the following results in games that ultimately ended by exactly one run:

Favorite Result	Historical Figure
Record	8,200-6,410
Win rate	56.1%
ROI	-5.7%
Profit/Loss	-$124,725

The favorite subset contains 14,610 graded favorite decisions, which is smaller than the 14,968 one-run games in the overall count. The historical data presented on this page does not specify why the remaining one-run games are outside that favorite subset, so they should not be assumed to have the same grading treatment.

More importantly, the -5.7% ROI should not be interpreted as a pregame system telling bettors to fade favorites in “one-run games.” The one-run classification is only known after the game is over. This result is descriptive: among completed games that finished by one run and had a graded favorite in the subset, favorite moneyline pricing produced the published negative ROI.

Why One-Run Games Matter for MLB Runline Betting

A standard favorite runline of -1.5 requires the favorite to win by at least two runs. If the favorite wins by exactly one, the moneyline cashes but the -1.5 runline loses. Conversely, an underdog taking +1.5 covers when it wins outright or loses by exactly one run.

Because 28.4% of the games in this historical sample ended by exactly one run, run distribution deserves serious consideration when comparing moneyline and runline prices. But the one-run frequency does not mean +1.5 underdogs are automatically profitable. The price paid for the extra run and a half still determines the break-even threshold and expected value.

For the broader historical comparison, see our MLB runline betting trends since 2004. To compare moneyline and alternate runline structures for a specific matchup, use the MLB runline calculator.

What This One-Run Game Data Can and Cannot Tell You

The data supports several useful conclusions. One-run games are common in MLB, a large share of baseball outcomes sit near the standard runline boundary, and favorite moneyline pricing in the retrospective one-run subset was not profitable in the published sample.

What the data does not establish is a pregame rule for identifying which games will finish by one run. It also does not prove that a blanket +1.5 runline strategy is profitable, because runline prices vary and profitability depends on those prices rather than cover percentage alone.

If you want to test whether a narrower pregame condition changes the distribution, the condition should be defined before looking at the result and then evaluated using sample size, price, ROI, and a plausible market explanation. That is the same framework used throughout our MLB historical betting systems research archive.

MLB One-Run Game Key Takeaways

• 14,968 of 52,697 MLB games in the historical sample were decided by exactly one run.
• That equals a 28.4% one-run game rate.
• Favorites in the graded one-run subset went 8,200-6,410 (56.1%).
• The published favorite result was -5.7% ROI and -$124,725.
• The one-run designation is retrospective, so it should not be treated as a pregame betting system.
• The high frequency of one-run finishes helps explain why the difference between moneyline and -1.5/+1.5 runline pricing matters so much in baseball.

Related MLB Betting Research

• MLB Betting Trends Since 2004: Favorites, Runlines & Totals
• MLB Runline Betting Trends Since 2004
• MLB Favorites vs Underdogs: Win Rates & ROI
• MLB Home Underdogs: Historical Win Rate & ROI
• MLB Runline Calculator