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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.
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