MLB culture is fascinated with history and legacy — measuring every great play and player against the legends that came before them. The league has existed for 149 years and, at this point, it's almost impossible to pull something off that's never been done before. That means the greatest accomplishments in modern baseball are always accompanied by "the first player since ..." or, "joins an exclusive club of ..."
The 2025 season has already provided plenty of examples. Kyle Schwarber clubbed four home runs in a single game last month, just the 15th time that's happened in MLB history. We saw an immaculate inning and a player hit two home runs in a single inning, both things that have happened less than 100 times in MLB history. We've had a triple play, a cycle, a walk-off grand sam, an inside-the-park grand slam and even a player homering from both sides of the plate in the same game.
All are storied accomplishments, but you may be surprised to learn how rare each event actually is.
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What are the rarest events in baseball?
Event | Total | Frequency | Last Happened |
|---|---|---|---|
Homering from both sides of the plate in the same inning | 3 | Once every 81,317 games | July 30, 2012 |
20+ K in a game | 5 | Once every 48,790 games | May 11, 2016 |
2 grand slams in a game | 12 | Once every 20,329 games | July 27, 2009 |
Unassisted triple play | 12 | Once every 20,329 games | Aug. 23, 2009 |
10+ RBI in a game | 12 | Once every 20,329 games | Sept. 19, 2024 |
Hitting for the natural cycle | 13 | Once every 18,766 games | Sept. 13, 2006 |
4 HR in a game | 15 | Once every 16,263 games | Aug. 28, 2025 |
Perfect game | 17 | Once every 14,350 games | June 28, 2023 |
Home run on the first pitch of MLB debut | 31 | Once every 7,869 games | April 4, 2021 |
Stealing from first to home in a single AB | 48 | Once every 5,082 games | May 27, 2019 |
2 HRs in one inning | 67 | Once every 3,641 games | May 2, 2025 |
Immaculate inning | 97 | Once every 2,515 games | Sept. 3, 2025 |
Inside the park grand slam | 223 | Once every 1,094 games | June 30, 2025 |
Walk-off grand slam | 250 | Once every 976 games | June 9, 2025 |
Hitting for the cycle | 273 | Once every 894 games | July 12, 2025 |
No-hitter | 326 | Once every 748 games | Sept. 4, 2024 |
Homering from both sides of the plate in the same game | 386 | Once every 634 games | Sept. 8, 2025 |
Triple play | 740 | Once ever 330 games | Aug. 12, 2025 |
This is only a partial list, winnowed down to things that, subjectively, have the most cultural cache. You can check out a full list here that includes some things you probably never even thought of, like players with three or more sacrifice flies in the same game.
On our list, the rarest accomplishment by far is homering from both sides of the plate in the same inning. It's been done 386 times in a game, but only three times in MLB history in a single inning — Carlos Baerga did it for the Guardians in 1993, Mark Bellhorn did it for the Cubs in 2002 and Kendrys Morales did it for the Angels in 2012.
By the numbers, the rarest accomplishment of this season was clearly Schwaber's four-homer game, but don't forget he wasn't the only one to do it. Rookie Nick Kurtz did it for the A's on July 25, and Eugenio Suárez did it for the Diamondbacks back on April 26. That's three times in one season for a feat that hadn't been done since 2017 and was seen just six times in the past 25 years.
Coming into this season, a four-homer game had happened, on average, just once every 20,149 games. That rate has been cut to once every 16,263 games now. While the pace may be accelerating, don't bet on seeing it happen again for at least a few years.
The other big statistical outlier this season is the lack of no-hitters. At the historic pace, we'd expect to see about three no-hitters in a 162-game season — but, as of this writing, we haven't seen one yet this year. We haven't had a full season without a no-hitter since 2005, but the Dodgers losing two in the ninth inning in just the past week is a historic outlier of its own that could explain the other. With a few weeks left in the season, there are still a few pitchers with a chance to throw the first no-no of the year.