What is a walk-off in baseball? How Diamondbacks' Ketel Marte made history with NLCS hit

When the Arizona Diamondbacks' Ketel Marte's hit brought in Pavin Smith on Thursday to give his team a 2-1 win over the Philadelphia Phillies in Game 3 of the NLCS, it gave the Diamondbacks their third-ever walk-off playoff victory.

But what is a walk-off in baseball?

The term has brought some confusion to fans over the years.

Here's a look at what it means to hopefully alleviate that confusion over one of the most exciting ways to win in sports after Arizona's big victory in that fashion against the Phillies.

The most memorable walk-off in Diamondbacks history came when Luis Gonzalez's hit in the bottom of the ninth of Game 7 of the 2001 World Series gave Arizona a 4-3 series win over the New York Yankees.

Could we see more walk-off wins in the 2023 MLB Playoffs?

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What is a walk-off in baseball?

A walk-off in baseball occurs when the home team takes the lead in the bottom of the ninth inning or in extra innings, giving them the victory in the game, like Marte's hit gave Arizona the 2-1 win over the Phillies on Thursday night.

There is no need for the game to continue, since the home team bats last, so the game immediately ends with the home team recording the win.

Walk-offs can occur any way the home team can score a run. It can come via a hit, an error, a walk or a hit by pitch with the bases loaded, a sacrifice fly, a wild pitch, a passed ball, or even with a balk (yes, a walk-off balk).

The MLB glossary explains how teams can adjust their defense in a potential walk-off situation (and the Phillies did this in Game 3 by bringing their defense closer in the bottom of the ninth):

"In walk-off situations with fewer than two outs and a runner on third base, a visiting team will typically adjust its defense to maximize the chances of stopping a runner at home plate. The visitors typically bring the infield in, so the infielders are positioned closer to home plate. Sometimes, a manager will even bring one of his outfielders into the infield to maximize the chances of throwing home for an out on a ground ball. Outfielders will almost always play very shallow to have a chance at a double play on a flyout or to throw the runner out at home on a single."

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Why is a walk-off a big deal?

It is the equivalent of a football team winning in sudden-death overtime, or a soccer team winning on the final penalty kick - it immediately ends the game (once the hitter has safely reached base).

Walk-off hits tend to bring out big celebrations from MLB teams (just look at how the Diamondbacks mobbed Marte after his hit on Thursday).

Walk-off wins can give teams momentum and have potentially flipped postseason series in the MLB Playoffs.

More: Ketel Marte, survivor of Diamondbacks' misery, walks off Phillies in stunning NLCS win

Memorable walk-offs in MLB history

In 1960, the Pittsburgh Pirates' Bill Mazeroski hit a walk-off home run in Game 7 of the World Series to give the Pirates the title over the New York Yankees.

In 1993, the Toronto Blue Jays' Joe Carter hit a 3-run walk-off homer to give his team the World Series title.

In 1951, Bobby Thompson hit a walk-off home run against the Brooklyn Dodgers to give the New York Giants the pennant.

In 1988, Kirk Gibson hit a walk-off home run over Eckersley, who later coined the phrase. Gibson's memorable shot gave the Los Angeles Dodgers the win in Game 1 of the World Series.

The Boston Red Sox's David Ortiz walked off the New York Yankees in Game 4 of the ALCA in 2004 with a two-run homer that sparked Boston's amazing comeback in the series.

And not to be forgotten, especially in Arizona, was Gonzalez's blooper against Mariano Rivera, that gave the Diamondbacks their first (and only) World Series title.

Reach Jeremy Cluff at jeremy.cluff@arizonarepublic.com. Follow him on X, formerly Twitter @Jeremy_Cluff.

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This article originally appeared on Arizona Republic: What is a walk-off in baseball? How DBacks' Ketel Marte made history