What is a Ground Rule Double? Definition and Examples
A ground rule double is a two-base award given to a batter when a fair ball bounces over or becomes lodged in an outfield wall, fence, or other obstacle, with all runners advancing two bases from their position at the time of the pitch.
What is a Ground Rule Double?
A ground rule double is a scoring play where a fair ball bounces over the outfield wall, becomes lodged in a fence, or gets stuck under a barrier, and the umpire awards the batter second base and all runners two bases from where they stood at the time of the pitch. It is called a "ground rule" double because the award follows the ground rules of the specific ballpark — every stadium has its own quirks, but the two-base award is standard under MLB Rule 5.05(a)(6) through (9).
How It's Scored and Measured
The umpire signals a ground rule double by raising two fingers and pointing to second base. The official scorer records a double for the batter and advances all runners two bases. The rule applies when:
- A fair ball bounces over the outfield wall in flight
- A fair ball becomes lodged in the outfield wall or padding
- A fair ball is touched by a spectator or foreign object while in the field of play
- A fair ball bounces into the stands or dugout
The key distinction: if the ball clears the wall on the fly (without bouncing), it is a home run. If it bounces over, it is a ground rule double. Runners do not score automatically — a runner on first advances to third, a runner on second scores, and a runner on third scores. The batter always gets second base.
Worked Example: Real Numbers
In a 2024 game at Fenway Park, Boston's Rafael Devers hit a line drive that bounced off the top of the Green Monster and caromed over the wall. The umpire ruled a ground rule double. Devers was credited with a double, and a runner on first advanced to third. The play added one run to the team's expected run total — a runner on third with one out scores roughly 50% of the time, versus a runner on second with no outs scoring about 40% of the time.
Another example: at Tropicana Field, a ball hit into the catwalks above the field is governed by special ground rules. If a ball hits a catwalk and stays in play, it is live. If it hits a catwalk and bounces down into the field, it is a ground rule double. If it hits a catwalk and never comes down, it is a home run. These ballpark-specific rules change the award.
Why It Matters
Ground rule doubles affect run expectancy, fantasy scoring, and betting lines. A double is worth more than a single in every scoring system — in standard fantasy, it is worth 2 points versus 1 for a single. In DFS, a ground rule double counts as a double, not a home run, so the batter does not get the home run bonus. For MLB betting, a ground rule double changes the over/under and run-line math because it removes the chance of an inside-the-park home run.
For front offices, ground rule doubles are not a separate skill — they are a function of ballpark dimensions and batted-ball luck. A hitter with a high pull rate in a ballpark with a short porch may accumulate more ground rule doubles, but the underlying exit velocity and launch angle matter more. Statcast does not track ground rule doubles separately; they are included in the player's double total.
Limitations and Common Misconceptions
The most common misconception: a ball that bounces over the wall is a home run. It is not — it is a ground rule double, even if it would have cleared the wall on a higher trajectory. Another misconception: runners advance an extra base if the throw goes out of play on a ground rule double. They do not — the two-base award is fixed, and the ball is dead immediately.
A ground rule double is not the same as an automatic double for a ball that sticks in a fence. If the ball becomes lodged in the fence and the fielder retrieves it, the ball is live and the batter may attempt a triple — that is an "inside-the-park" situation, not a ground rule double. The umpire only awards two bases if the ball is unreachable or leaves the field.
Related Terms
In Legends Deck
Legends Deck uses park-specific ground rule logic: each stadium has a wall height and bounce profile, and when a batted ball reaches the warning track with enough exit velocity, the sim checks whether it clears the wall on the fly or bounces over for a ground rule double. Card ratings for power and launch angle determine how often a player turns a wall-banger into a double versus a home run. A player with high raw power but low launch angle will rack up ground rule doubles in deep parks, while a high-launch-angle hitter clears the wall more consistently.