By Cliff Corcoran

With his four home runs in a single game against the Cardinals on Tuesday night, Reds utility man Scooter Gennett became arguably the least likely member of one of baseball's most exclusive clubs. Major League history has thus far included 711 triple plays, 307 cycles, 296 no-hitters and 23 perfect games, but Tuesday night marked just the 17th time in the 142-year history of Major League Baseball that one man hit four home runs in a single game.

Among the 15 live-ball era hitters to hit four home runs in a single game, Gennett is the least likely by virtually every measure. No live-ball era hitter had fewer career home runs prior to his four-homer game or hit home runs less often (on a per-plate-appearance basis) prior to his feat.

At the same time, only two of those 15 live-ball era hitters had fewer career plate appearances heading into his four-homer game than the 27-year-old Gennett's 1,754. I don't believe that Tuesday night's performance heralds the arrival of a new power stroke for the 5-foot-10 Gennett. However, given some of the power surges we've seen from hitters in recent years, and the fact that every other four-homer hitter has played his last Major League game (assuming Josh Hamilton won't make it back), I think it's important to frame Gennett's performance in the proper context.

With that in mind, I took the career and single-season home-run frequencies for each of those 15 live-ball era hitters prior to their four-homer games and combined them into a single PA/HR statistic weighted by plate appearances. Doing so double-counts the season of the four-homer game, giving what I believe to be appropriate added weight, while still considering the career rates far more heavily.

By that measure, the most prolific home run hitter at the time of his four-homer game wasn't Willie Mays, Mike Schmidt, Lou Gehrig or Carlos Delgado, but 25-year-old Cleveland slugger Rocky Colavito, who had homered once every 17.1 plate appearances in his career prior to going deep four times against the Orioles on June 10, 1959, and once every 15.4 times that season prior to that game, for a weighted average of 16.9 PA/HR. Gehrig (17.7) and Delgado (18.3) come in second and third. Mays (19.2) and Schmidt (19.8) rank fifth and sixth, behind the Braves' Bob Horner (18.9).

The least likely four-homer-game hitters of the live-ball era by that measure are as follows.

5. Mike Cameron, Mariners, 31.5 PA/HR

In 2001, the year before his four-homer game against the White Sox, Cameron turned in his best single-season performance at the plate, hitting .267/.353/.480 (123 OPS+) with 25 home runs and 110 RBIs in his age-28 season for a Mariners team that won 116 games. He would hit 25 home runs again in '02, but he would surpass that total just once in his 17-year career, when he hit 30 for the Mets in 2004. Among the 14 live-ball era hitters to hit four home runs in a game prior to Gennett, only Mark Whiten (33.6 PA/HR) homered less often in his career than Cameron, who went deep once every 28.4 plate appearances over those 17 seasons. That said, it's worth noting that Cameron spent the heart of his career, eight seasons from the age of 27-34, playing his home games in home-run suppressing ballparks in Seattle, Queens and San Diego, while his four-homer game came on the road in the homer-friendly new Comiskey Park.

4. Gil Hodges, Dodgers, 31.8 PA/HR

Hodges was one of the premier power-hitters of the 1950s. His 310 home runs from 1950-59 ranked second in the Majors, behind only teammate Duke Snider's 326. From 1950-56, Hodges averaged 34 home runs a year, twice reaching 40 in a single season. However, Hodges' four-homer game came in August 1950, while he was still establishing his power-hitting bona fides at the age of 26. At that point, his career high was the 23 home runs he had hit in 1949, and he had just 19 to his name entering that August 31 game against the Braves. Hodges would hit 13 more over his final 36 games, four on the final day of August and nine in September. He went deep 40 times the next year and finished his 18-year career with 370 roundtrippers, having homered once every 21.9 plate appearances.

3. Joe Adcock, Braves, 33.9 PA/HR

Adcock is a very similar case to Hodges. Later in his career, he would have seasons of 38 and 35 home runs, and over 17 seasons, he would hit 336 roundtrippers at a rate of one every 21.7 plate appearances. However, at the time of his four-homer game on July 31, 1954, he was a 26-year-old still establishing his power stroke in the Major Leagues. Entering the 1954 season, Adcock had never hit more than 18 home runs in a single season, but he surpassed that mark in his four-homer game, which saw him hit his 16th, 17th, 18th and 19th home runs of that season. Still, he would hit just four more over the remainder of the season, which came to a premature end when his thumb was broken by a pitch in early September, and just 15 in an injury-shortened 1955 season. In 1956, he would hit 15 home runs in July alone on his way to a career-high 38. Famed for both his four-homer game and the prodigious distance of his clouts, Adcock is now remembered as a key power bat for the great Milwaukee Braves teams of the 1950s, but prior to his four-homer game, his potential was greater than his performance.

2. Mark Whiten, Cardinals, 39.8 PA/HR

Speaking of the difference between potential and performance, "Hard Hittin'" Mark Whiten appeared to be on the Hodges/Adcock track when he hit four home runs against the Reds on Sept. 7, 1993 at the age of 26. Rated the 25th-best prospect in baseball by Baseball America prior to the 1991 season, he was a strapping 6-foot-3 switch-hitting outfielder with a rocket arm and what seemed like untapped power potential at the plate. Prior to '93, he had never hit more than nine home runs in a season and had been traded twice (from Toronto to Cleveland to St. Louis). That year, however, he had 18 home runs heading into his landmark performance against the Reds, and emerged from that game with 22 on his way to 25 on the season. That would prove to be his career high. Plagued by injuries and off-field issues, Whiten hit just 26 home runs over the next two seasons, 22 in a 1996 season split between three teams, and just 12 more before his Major League career came to an end with 10 homerless plate appearances for Cleveland in 2000 at the age of 33.

1. Scooter Gennett, Reds, 45.7 PA/HR

Gennett is an even greater outlier on this list than the numbers would suggest. Cameron, Hodges, Adcock and Whiten were all in excess of six feet tall and had undeniable power potential at the plate. Gennett is listed as 5-foot-10 and had never reached double digits in home runs in six professional seasons prior to hitting 14 for the Brewers last year. Prior to Tuesday night, he was on pace for just nine more roundtrippers this season and had gone 97 plate appearances without a home run prior to his first-inning shot off Adam Wainwright. Having more than doubled his season total, Gennett's four-homer game has increased his homer pace to 20. Yet, even that would be the third-lowest season total for a player who hit four home runs in a game after the two 19th century hitters and stocky White Sox outfielder Pat Seerey, a powerful but undisciplined hitter who was traded a month before his four-homer game, finished that 1948 season with 19 home runs, and washed out of the Majors the next year at the age of 26. More likely, Gennett will fall short of Seerey's total, and he could fall shy of Bobby Lowe's 17 home runs in 1894, as well.

All of that said, entering Thursday's action, Gennett has averaged one home run every 18 plate appearances this season, a 36-homer pace over 650 PA. Again, I do not believe that Gennett's four-homer game will prove to be a transformative moment in his career, but we've seen crazier things happen.

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Cliff Corcoran is a Sports on Earth contributor and a regular guest analyst on the MLB Network. An editor or contributor to 13 books about baseball, including seven Baseball Prospectus annuals, he spent the last 10 seasons covering baseball for SI.com and has also written for USA Today and SB Nation, among others.