There are countless ways, of course, to try and rank where Scooter Gennett's unthinkable five-hit, four-homer, 10-RBI game ranks in the annals of baseball history. Begin with the scale of unlikelihood; in that way, it has to rank more or less at the top. Entering the game, Gennett had three home runs all season. He's so vividly not a home-run hitter -- he's a scrappy middle infielder, as all men named Scooter are.
Scooters do not hit four homers in a game.
But Gennett did so in the Reds' 13-1 win over the Cardinals on Tuesday, becoming the 17th player in baseball history to hit four homers in a single game. He is, almost without question, the most improbable of the 17.
• Electric Scooter! Slam 1st of 4 historic HRs
(The only player who is even close, I suppose, was the first to do it, a popular second baseman named Bobby Lowe. Lowe was a very good player, but that was in 1894. Home runs were rare things then -- 18 homers were enough to lead the league. When Lowe hit his fourth, the crowd was so overcome with shock and glee that it began throwing coins on the field in his honor. The money was collected and totaled $160 -- about $4,000 with inflation).
But forget the wonderful "any player on any day" absurdity of this. Where does Gennett's game rank, simply, by the numbers? Well, you can just go by total bases. Gennett became the sixth player since 1900 to have at least 17 total bases in a single game.

1. 19 TBs: Shawn Green on May 23, 2002
   
2. 18 TBs (tie): Josh Hamilton on May 8, 2012
   
3. 18 TBs (tie): Joe Adcock on July 31, 1954
   
4. 17 TBs (tie): Scooter Gennett on June 6, 2017
   
5. 17 TBs (tie): Mike Schmidt on April 17, 1976
   
6. 17 TBs (tie): Gil Hodges on Aug. 31, 1950

But here's something fun: There's a statistic that goes back to legendary sports statistician Pete Palmer called RE24 -- Run Expectancy based on 24 base-out states. Yes, it can sound a bit daunting, but it's really pretty easy. There are 24 possible situations for any hitter in any inning. These depend on how many players are on base and how many outs there are. For example, a hitter can come up with no one on base and one out. He can come up with the bases loaded and two outs. He can come up with men on second and third and no outs. And so on. There are 24 possible scenarios like these.
Each state has what you would call a run expectancy -- that is, how many runs you would expect to score. If there is nobody on and two outs, how many runs would you expect the team to score? In that scenario, the run expectancy is minuscule -- less than a tenth of a run. If the bases are loaded with nobody out, though, you would expect to score two runs or more. The run expectancy in that scenario is around 2.3 runs.

By looking at the greatest single RE24 games, you will find the hitters that provided the most runs above the expectation. The top seven RE24 games in baseball history are:
1. 9.5 RE24: Mark Whiten, 4-for-5, 4 HRs, 12 RBIs on Sept. 7, 1993
Hard hittin' Whiten was playing for the Cardinals and facing the Reds, a mirror image of Gennett's magical game on Tuesday. Coincidentally, Whiten and Gennett are the only two players in baseball history to have a grand slam among their four homers in a single game.
Whiten hit his slam in the first inning with two outs to give the Cards a 4-0 lead. He fouled out in the third, then hit a three-run homer in the sixth. One inning later, Whiten hit another three-run homer, and in the ninth -- with his team already up 13-2 -- smashed a two-run homer. He created 9.5 more runs than the average player in a single game.

2. 9.4 RE24: Anthony Rendon, 6-for-6, 2B, 3 HRs, 10 RBIs on April 30, 2017
Funny, it seems like only yesterday that we were talking about this as the greatest offensive day in baseball history. Rendon began with a two-run single, followed with a solo homer, then a three-run homer, a three-run double, a regular old single that didn't score anybody and finally a solo shot to finish it off.

3. 9.3 RE24: Phil Weintraub, 4-for-5, 2 2Bs, 3B, HR, 11 RBIs on April 30, 1944
Weintraub was an aging veteran playing out the string as the war raged on; he lived a fascinating baseball life that was filled with a lot of pain. But that's a story for another time. This was his magical day. Weintraub doubled in two in the first, walked with the bases loaded in the second, tripled with the bases loaded in the third and doubled with the bases loaded in the fourth. Coming up with the bases loaded in three consecutive innings is pretty impressive. He later hit a three-run homer. The only thing Weintraub did not do on this day was hit for the cycle, falling a single short.
4. 9.1 RE24: Norm Zauchin, 4-for-5, 2B, 3 HRs, 10 RBIs on May 27, 1955
Zauchin was a 25-year-old rookie in 1955, and on his grand day, he began with a two-run homer off Washington pitcher Bob Porterfield. Next time up, Zauchin faced a different pitcher, Dean Stone. He hit a grand slam. Next time up, the pitcher was Ted Abernathy. Zauchin hit an RBI double and followed an inning later with a three-run homer.
Zauchin came up once more with a chance to get his fourth homer, this time off pitcher Pedro Ramos. He struck out.
5. 8.6 RE24: Alexander Rodriguez, 4-for-5, 3 HRs, 10 RBIs on April 26, 2005
A-Rod hit a three-run homer off Bartolo Colon in the first, a two-run homer off Colon in the third and a grand slam off Colon in the fourth. In his career, Rodriguez hit .411 and slugged a nice even 1.000 against Colon, with eight homers in 63 plate appearances.

6. 8.6 RE24: Fred Lynn, 5-for-6, 3B, 3 HRs, 10 RBIs on June 18, 1975
This was during Lynn's extraordinary 1975 season, when he won the American League Rookie of the Year Award and the AL MVP Award. He homered in the first and second innings and tripled in the third inning. That's about as good a start as any player in baseball history. Lynn later added a single and a three-run homer.
7. 8.3 RE24: Scooter Gennett, 5-for-5, 4 HRs, 10 RBIs on June 6, 2017
A little more than a month after Rendon's amazing game, Gennett put up his own historic performance. How rare a game was it? Only Whiten had managed at least 10 RBIs in a four-homer game. Only Green, Hamilton, Adcock and Carlos Delgado had managed to hit four home runs in a game and not make an out.
• DYK: Gennett has a slam and career night
Gennett began with a run-scoring single. His grand slam in the third was made possible by a bizarre decision from Cardinals manager Mike Matheny, who decided to challenge the fact that his own outfielder had caught the ball (a Reds player had tagged up and scored, Matheny challenged and won, taking the out off the board and leading to the slam).
• Reds in awe of Gennett's historic power display
Gennett hit his second homer in the fourth, a two-run shot. He hit his third homer in the sixth, a solo blast. Gennett finished it off with a two-run home run in the eighth.
You can argue things a lot of different ways. But when you add up actual offensive damage, the situation of each hit and the sheer improbability of it all, yeah, I think you could call Gennett's day the greatest in baseball history.