Hitting one grand slam in a season is hard enough. But hitting a large handful of them? That takes an incredibly rare combination of both skill and a little luck.
From 1901 -- the season the American League began play -- through 2017, a total of 146 different players had recorded at least one 40-homer season. Four-hundred and forty-four had compiled at least one 30-homer campaign. But only 24 players have knocked as many as four grand slams in the span of one regular season, making a handful of slams truly one of the rarer feats a hitter can set out to accomplish after he digs into the batter's box on Opening Day. Even as MLB hitters went homer-crazy and clubbed a record 6,105 roundtrippers in 2017, only 133 of them -- or roughly 2.2 percent -- came with the bases loaded. Giancarlo Stanton's 59-homer 2017 season, which represented the most serious chase for the home run record by anyone since Barry Bonds, did not include a single grand slam.
Perhaps it's the rare nature of the grand slam that has kept it from being included among the most memorable homers in baseball history. Paul Konerko's grand slam off Astros reliever Chad Qualls turned the tide in Game 2 of the 2005 World Series for the White Sox, but it came a little too early in the Series to be revered. The same goes for Tino Martinez's tiebreaking slam for the Yankees in Game 1 of the 1998 Fall Classic, or Ken Boyer's slam for the Cardinals against the Bronx Bombers in Game 4 in 1964. Yankees first baseman Bill Skowron is the only player to hit a grand slam in Game 7 of a World Series, though the Bombers already held a 5-0 lead over the Dodgers when he connected in 1956. Kent Hrbek's Game 6 slam was instrumental in the Twins' first championship in 1987, but it has not lived on in the national consciousness in the same way that non-slam homers hit by the likes of Kirk Gibson, Bill Mazeroski, Joe Carter or Bobby Thomson have.
Still, it's worth remembering the sluggers who simply inflicted a ton of damage in one calendar year, even if the moments were fleeting. Below are the players who have bucked the odds and recorded the most grand slams in a single season.
1 (tie). 6 grand slams -- Don Mattingly (1987) and Travis Hafner (2006)
The 1987 season marked the last of Mattingly's three consecutive years with at least 30 dingers. It also capped off a breathtaking run of dominance for Mattingly through his first four full seasons as a Major Leaguer, in which he …
• …won the 1984 AL batting title with a .343 average at age 23.
• …led the Majors with 145 RBIs and captured the AL MVP Award in '85.
• …paced the Junior Circuit in hits (238), doubles (53), slugging (.573), OPS (.967) and total bases (388) in '86.
• …tied a MLB record with homers in eight consecutive games, while also hitting those record six grand slams, in '87.
Mattingly clubbed all six of his slams out of the No. 3 spot in manager Lou Piniella's lineup, saving three of them for the home crowd at Yankee Stadium. He did his damage early, clubbing all his slams before the fifth inning, and hit them in bunches: Nos. 3 and 4 came within a week of each other in July, and Nos. 5 and 6 were hit within five days of each other at the end of September. Mattingly's record-breaker came off Red Sox pitcher Bruce Hurst -- a lefty who had previously held Mattingly to a .217 average -- and traveled up into the third deck in right field at Yankee Stadium.
Perhaps the most fascinating part about Mattingly's six-slam 1987 campaign is that he did not hit another one in any other season of his excellent 14-year career. Prior to '87, Mattingly had hit .250 with just one extra-base hit in 52 career at-bats with the bases loaded.
''I can't explain it,'' said Mattingly after slam No. 6. ''I basically haven't done anything different other than try to hit the ball hard. Before, I would hit a sacrifice fly with the bases loaded. Now, I think of hitting the ball hard. Consequently, if I get the ball in the air, it carries.''
Hafner didn't end his career with the same cachet as Mattingly, but he was a player who could hit the ball as hard as anyone -- particularly in 2006, his best season as a Major Leaguer. The Indians' designated hitter paced the AL with a .659 slugging percentage and 1.097 OPS while also clubbing 42 homers and driving in 117 runs on the way to his second straight top 10 finish in MVP voting. Six of those taters came with the bases loaded, and five of those came in front of the Tribe's home crowd at what was then known as Jacobs (now Progressive) Field.
Pronk, as he was affectionately called by fans and teammates alike, didn't wait long to strike, belting all six of his slams within the first three pitches of his at-bats. Four of them came appropriately enough, from the cleanup spot. Just as Mattingly's six grand slams helped the Yankees tie the former team record of 10 in one season, Hafner's half-dozen helped the 2006 Indians tie the current record of 14 alongside the 2000 A's. Hafner was 10 years old when Mattingly assaulted the record books, and suddenly his name stood alongside one of his childhood heroes.
"It's pretty cool to tie a Major League record," said Hafner. "Mattingly was one of the best hitters in the game. I liked to watch him on TV when I was young."
Hafner was unfortunately forced onto the disabled list in early September with a broken right, leaving a small "what-if" taste to his storybook season.
3 (tie). 5 - Ernie Banks (1955), Jim Gentile (1961), Richie Sexson (2006) and Albert Pujols (2009)
The 1955 season was a coming-out party for the power of Banks, who followed up his second-place finish in the '54 NL Rookie of the Year vote with 44 homers for the Cubs. Those 44 roundtrippers set a record at the time for the most single-season homers by a shortstop, and five of them came with the bases loaded. That stood alone as an NL record until Pujols matched Banks 59 years later, though the former Cardinals slugger might not pick any of them as his favorite slams; he hit one in his first collegiate game and also for his 600th career homer on June 3, 2017.
Gentile's five-slam season was memorable for its fast start, as he hit four of them before the All-Star break. That included two in the same game (on consecutive pitches, no less) for the Orioles slugger on May 9, 1961, against the Twins, which made Gentile the fourth player to ever accomplish that feat. Gentile's all-around power stood out in '61; he hit 46 of his 179 career homers in that single season and finished third in the MVP vote.
Sexson was no stranger to the grand slam, having hit nine of them entering the 2006 season. Though his campaign was ultimately overshadowed by Hafner's, Mariners fans who came to Safeco Field on Aug. 8, 2006, can probably recall his dramatic walk-off slam against the Devil Rays in the bottom of the 10th inning.
7 (tie). 4 -- 18 different players
This is where the random nature of the grand slam really starts kicking into overdrive. This group of 18 has some of the famous sluggers in history, including Lou Gehrig (whose 23 grand slams rank second all-time), Babe Ruth (who hit four slams in 1919 while also winning nine games in his last season as a regular pitcher), Ralph Kiner, Mike Piazza and Edgar Martinez.
Right alongside them is shortstop Alexei Ramirez, who allocated four of his 21 rookie-season homers for bases-loaded situations for the White Sox in 2008, and then never hit more than 18 dingers in a season after that. Infielder Ray Boone knocked four slams for the Indians and Tigers in 1953, nearly half as many as his son Bob (two grand slams) and grandsons Aaron (two) and Bret (six) hit during their combined 48 seasons of Major League service time. Vince DiMaggio never earned the acclaim of his brothers, Joe and Dom, but he did hit a nearly one-quarter of their combined career grand slams (18) in 1945 alone.
Only one player (Ryan Howard) has ever hit more homers in his first 250 career games than Rudy York, and that included four grand slams for the Boston Brave in 1938, his second full season. Scooter Gennett, meanwhile, had homered just 35 times over his first four big league seasons before he became the first player to ever record a four-homer game and hit four slams within the same campaign in 2017. Just like fans can never guess if they'll see a grand salami when they show up at the ballpark, it's just about impossible to guess when a hitter will strike jackpot -- again and again and again -- within the same calendar year.
Matt Kelly is a reporter for MLB.com based in New York. Follow him on Twitter at @mattkellyMLB.