There is perhaps no instance in baseball more exciting than a walk-off grand slam. It doesn’t normally happen that often, but if you thought, “Wow, there seemed to be an abnormally high number of walk-off grand slams this year,” you’re actually right.

During the 2021 regular season, there were six walk-off grand slams. That tied the fourth-highest single-season total in MLB history, joining the 1963, 1980, 1995, 2006, 2011, 2014 and 2017 seasons. The top three seasons for walk-off slams were 2018 (nine), 2002 (eight) and 2008.

Here’s a rundown of every walk-off slam this year.

June 15: Jose Altuve
The first walk-off slam of the year came from a player known for hitting walk-off homers (see: 2019 ALCS vs. Aroldis Chapman). On June 15, with the Astros down one run vs. the Rangers in the ninth inning, Carlos Correa thrilled the crowd with a game-tying homer to force extras. But the biggest heroics were yet to come.

In the 10th, Texas pulled ahead on a single from Nate Lowe. Then came Houston's turn, and two walks later, Altuve dug in. He took one strike from Demarcus Evans and then crushed a cutter a projected 370 feet to left field. It was the perfect gift for Astros manager Dusty Baker, who was celebrating his 72nd birthday.

Altuve’s slam would have been a homer in 15 out of 30 stadiums, and it would have stayed in the park had the game been at Globe Life Field instead of Minute Maid Park. It was the first of three grand slams Altuve hit in 2021 -- he also cleared the bases on July 1 and July 30 -- which doubled his previous career total of three.

June 20: Shed Long Jr.
By the end of the season the Mariners had exceeded expectations, sweeping the future AL East champion Rays in June and later finishing two games back of what could have been their first playoff berth since 2001. Seattle capped that Tampa Bay series with a dramatic walk-off grand slam from Long, who had recently recovered from a right shin stress fracture. That slam came in just his 11th game of the season.

Seattle entered the bottom of the 10th with the score tied at two. After two Mariners reached via a single and a walk, Long batted with the bases full. Then, on a 1-1 pitch from Diego Castillo, Long pulled a slider a projected 348 feet over the right-field fence, delighting the Father's Day crowd and ending the series in exhilarating fashion. What better way for Long to get his first homer of 2021?

Long’s slam had a 96 mph exit velocity and would only have been a home run in just nine out of 30 ballparks, though it also would have gone out at Tropicana Field.

Hampered by injuries to his right shin, Long finished 2021 with just four homers. None were bigger than the walk-off slam.

July 17: Jacob Stallings
Entering the Mets-Pirates matchup, New York’s bullpen had been mostly spotless all year, and closer Edwin Díaz had not yet allowed a home run in 2021. However, down 6-0 entering the eighth, the Pirates scored five times to pull within one run of completing their comeback.

After a solo homer from Brandon Nimmo, Pittsburgh entered the bottom of the ninth down 7-5. A hit-by-pitch, a walk and a single loaded the bases, and Stallings stepped to the plate. He took a vicious cut at a first-pitch fastball that everyone, including Díaz, thought was popped up. But it wasn't. The ball sailed into the seats in the left-field corner, beyond the reach of left fielder Kevin Pillar.

That grand slam, which traveled a projected 346 feet with a 93.7 mph exit velocity, was a home run in only nine out of 30 stadiums and would not have gone out at Citi Field. The slam was one of four walk-offs from Stallings in 2021; the other three occurred on May 15, June 5 and July 31. Pittsburgh had a total of nine walk-off wins in 2021; Stallings alone ended nearly half of them.

July 29: Brad Miller
The Phillies had several comebacks against the Nationals in 2021, but only one ended with a walk-off-slam. In this memorable contest, the second game of a doubleheader, Miller came up in the eighth inning with the bases loaded after starter-turned-pinch-hitter Aaron Nola walked. On a 1-2 pitch from Sam Clay, Miller crushed a sinker 425 feet at a projected 105.8 mph to right field for the walk-off grand slam.

Miller's knock capped the largest comeback for Philadelphia since 2010. In a game they once trailed 7-0, the walk-off sealed a hard-earned doubleheader split.

Aug. 23: Travis Shaw
Shortly after returning to the Red Sox, who drafted him in 2011, Shaw threw himself the best welcome home party. After a game-saving RBI double from Rafael Devers in the 10th inning of a back-and-forth affair with the Rangers, Shaw stepped up to bat with the bases loaded in the bottom of the 11th.

With a full count, Shaw smashed a sinker from Dennis Santana a Statcast-projected 423 feet to right field (with a 103.5 mph exit velocity) to clear the bases and walk it off. Shaw appeared in just 28 regular-season games for Boston over the course of the season and hit .238, but for one night, "MLB: The Shaw" was alive and well.

Sept. 5: Daniel Vogelbach
This walk-off slam was the ULTIMATE way to end a game, and not just because it was exciting. Per MLB, an ultimate grand slam occurs when a team enters its final at-bat down three runs and wins on a grand slam, which is exactly what Vogelbach accomplished. This has happened 30 times in MLB history.

Vogelbach, who was pinch-hitting, had been supplanted by Rowdy Tellez on the depth chart. Milwaukee had already blown a chance to score in the eighth. But with one mighty swing, Vogelbach replaced any negativity at American Family Field with jubilation.