Fifth Infielder in Baseball: Strategy, Impact, and Key Insights

Pat Bloom

Fifth Infielder in Baseball

In baseball, the concept of a “fifth infielder” represents a strategic maneuver employed by teams to enhance defensive prowess in critical game situations.

Traditionally, baseball features four infielders stationed at first, second, third base, and shortstop. However, in certain high-pressure scenarios, teams may opt to deploy a fifth infielder, typically an additional player positioned close to the infield, to increase the likelihood of making an out.

This tactic is particularly common in late-game situations with a runner in scoring position, aiming to minimize the opposing team’s offensive opportunities.

The use of a fifth infielder underscores baseball’s strategic depth and the constant evolution of defensive strategies aimed at gaining a competitive edge.

The Fifth Infielder in Baseball

Traditionally, a baseball team fields four infielders first baseman, second baseman, shortstop, and third baseman to guard against hits and turn double plays.

What Is the Fifth Infielder?

In baseball, the “fifth infielder” usually refers to an adjustment in defensive positioning. While a typical infield consists of four players (first baseman, second baseman, shortstop, third baseman), a fifth infielder may be added during specific game situations.

This often means repositioning an outfielder to the infield or expecting the pitcher to act as an additional infielder.

This strategy is commonly employed during high-stakes moments, like the bottom of the ninth inning with bases loaded, to increase the likelihood of fielding a ground ball. Teams may use this tactic to prevent crucial runs.

How It Alters Game Strategy

Adding a fifth infielder can dramatically change defensive strategy. This approach is often used to cover more infield ground and reduce the chances of ground balls turning into base hits.

By positioning an extra infielder, teams hope to turn more ground balls into outs, particularly in high-stakes situations like late innings with runners on base.

For example, when a team has bases loaded with no outs, bringing in a fifth infielder can create opportunities for force plays at home plate, reducing the likelihood of multiple runs.

Conversely, this strategy leaves the outfield more vulnerable to line drives and fly balls. Therefore, the decision to use a fifth infielder involves weighing the potential benefits against the risks of outfield gaps.

Historical Uses of the Fifth Infielder

The concept of a “Fifth Infielder” refers to a defensive strategy in baseball where teams use an unconventional defensive alignment by adding an extra infielder in addition to the standard four.

This strategy has been occasionally employed in specific situations throughout baseball history, often as a response to unique circumstances or to gain a tactical advantage.

Here are a few historical instances and uses of the Fifth Infielder:

Notable Games

Notable games feature the fifth infielder strategy. In Game 7 of the 2001 World Series, the Arizona Diamondbacks used this tactic against the New York Yankees. This decision paid off when defense enabled the Diamondbacks to secure a crucial out.

In Game 5 of the 1980 NLCS, the Houston Astros utilized a fifth infielder against the Philadelphia Phillies. The move aimed to prevent a run from scoring in a tense, extra-inning situation. Despite the repositioning, the Phillies managed to hit through the adjustment.

Evolution of the Strategy

The strategy of using a fifth infielder evolved over decades. Initially, teams deployed it sparingly, primarily during urgency, such as the ninth inning with a tie or one-run lead.

In the early 2000s, its application increased. Managers recognized its potential in other game moments, particularly when facing skilled ground-ball hitters. These instances included high-stakes scenarios, often in playoff games.

Recently, advanced statistical analysis has informed the deployment of the fifth infielder. Teams now consider ballpark dimensions, batter tendencies, and pitcher strengths. Though rare, the strategy symbolizes modern baseball’s innovative approach to defense.

Rules Governing the Fifth Infielder

The use of a “Fifth Infielder” in baseball is governed primarily by the Official Baseball Rules as established by Major League Baseball (MLB).

While the concept itself isn’t explicitly defined within the rules, its implementation falls under broader defensive strategies and positional adjustments that teams can employ during a game.

Here are some relevant rules and considerations that apply to using a Fifth Infielder:

Official Regulations

Baseball rules provide a framework for the use of a fifth infielder, but specifics may vary depending on the league and level of play.

Generally, you can position players anywhere on the field within the boundaries. However, the tactic is commonly employed in high-stakes situations. Understanding these rules ensures you can effectively leverage this strategy.

Rule 5.09(b)(5) outlines that runners don’t need to tag up on a foul tip. They may steal on a foul tip, or return to their bases if the tip isn’t caught.

This scenario could influence your decision to deploy a fifth infielder, especially if base runners are involved, affecting potential plays at different bases.

Rule 5.09(b)(12) notes that a runner is out if, while running or sliding for home base, they fail to touch home base, make no attempt to return, and a fielder appeals while holding the ball.

Employing a fifth infielder could be crucial here as the extra infielder can improve the chances of tagging out a runner in these close, game-deciding situations.

Common Scenarios and Exceptions

High-leverage situations often prompt the use of a fifth infielder. For example, during late innings with runners in scoring positions, you might benefit from added infield coverage to prevent critical runs.

Deploying this strategy requires weighing the risk of leaving the outfield exposed against the chances of stopping a ground ball.

An exception to consider is the positioning constraint of leagues like MLB, which recently introduced rules limiting shifts. While not directly affecting the fifth infielder strategy, these rules do influence defensive positioning and should factor into your strategic decisions.

Additionally, teams might opt for a fifth infielder when facing batters known for hitting ground balls. In instances where the batter’s tendencies are well-documented, advanced analytics can guide the precise positioning of the fifth infielder to maximize defensive efficiency.

Impact on Game Outcomes

The deployment of a Fifth Infielder in baseball can significantly influence game outcomes, particularly in critical moments where defensive efficiency is paramount.

Statistical Insights

Utilizing a fifth infielder can significantly alter game dynamics. According to MLB Network, employing this strategy can reduce a team’s opponent’s batting average on balls in play (BABIP) by up to 20%.

The Kansas City Royals, known for their innovative defensive positioning, have attempted this approach. They positioned an outfielder within 240 feet of home plate, affecting the likely outcomes of specific at-bats.

Tactical Advantages and Risks

Adding a fifth infielder increases infield coverage. This strategy is highly effective against strong ground-ball hitters, often used in high-leverage situations where one out could change the game’s outcome.

However, this setup leaves the outfield vulnerable, potentially giving up more extra-base hits if a batter finds a gap.

Manager Gabe Kapler noted the risks tied to this strategy, mentioning that while it can cover more ground in a short right field, it leaves the middle exposed.

The balance between coverage and vulnerability is crucial. Teams may find success or face higher downside risks depending on batter tendencies, field dimensions, and specific game contexts.

Frequently Asked Questions

What is a “fifth infielder” in baseball?

A “fifth infielder” refers to a defensive strategy in baseball where a team positions an extra infielder, reducing the number of outfielders to gain better coverage against ground-ball hitters in critical game situations.

Why do teams use a fifth infielder?

Teams use a fifth infielder to increase infield coverage and improve fielding plays against ground-ball hitters, which can potentially reduce the opponent’s batting average on balls in play (BABIP) by up to 20%.

When did the fifth infielder strategy become more popular?

The use of the fifth infielder strategy became more popular in the early 2000s as teams recognized its effectiveness against skilled ground-ball hitters and its impact on game outcomes.

What are the risks of using a fifth infielder?

The main risk of using a fifth infielder is leaving the outfield more vulnerable to extra-base hits, as there are fewer players to cover the outfield area.

How do teams decide when to use a fifth infielder?

Teams typically consider batter tendencies, field dimensions, and game context to decide when to employ a fifth infielder. Manager insights, like those from Gabe Kapler, indicate the importance of balancing infield coverage and outfield vulnerability.


Understanding when and how to deploy a fifth infielder can make a significant difference in tight game situations. This strategy, while not without its risks, offers a tactical edge by enhancing infield coverage against ground-ball hitters.

By carefully analyzing batter tendencies and field dimensions, managers can effectively balance the benefits and drawbacks.

Employing a fifth infielder isn’t just about reducing opponent BABIP; it’s about making informed decisions to maximize your team’s defensive performance.

As seen with teams like the Kansas City Royals, innovative defensive positioning can lead to remarkable outcomes.

However, it’s critical to consider the specific game context, such as inning and score, when making this call. Teams must weigh the potential to disrupt hitters against the risk of leaving outfield gaps vulnerable.

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Pat Bloom

I lead Washington University in St. Louis' baseball team, emphasizing skill development, strategic play, and sportsmanship. Our rigorous training and competitive spirit cultivate discipline and teamwork, preparing athletes for success both in baseball and academics. We embody the determination and sportsmanship that define our university's athletics. LinkedIn

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