Minor Tenth: MiLB’s New Extra-Inning Rule

The new Minor League extra-inning rule has led to more small ball after the ninth inning. (via Minda Haas Kuhlmann)

Commissioner Rob Manfred is not afraid of making changes to baseball. His term, now in its fourth year, has been marked by a willingness to alter pieces of the game that have seemed permanent and untouchable. In the major leagues, he has instituted the no-pitch intentional walk and a limit on mound visits, both changes made with a view to quickening the pace of play. In a like spirit, he put through a shortening of the time between innings, which, by trimming advertising time and thus advertising money, showed how serious he was about the matter.

His spirit of experimentation has carried over into minor league ball, where he has been even more radical. In 2015, he brought the pitch clock to the upper two tiers of the minors, allowing pitchers limited time to begin their pitching motion before a ball would be called on them. This was a momentous change to a game that had never before operated under a clock. (Umpires did have the rulebook authority to enforce pace rules on pitchers (Rule 8.04), but in practice it had decayed long ago. Manfred apparently decided it required a visible clock to restore this authority.) Manfred hoped to bring that change to the majors in 2018, but pushback from the Players Association convinced him to hold off, at least for a season.

Early this year, he added another seismic rule change, this one across all levels of the minors, again aimed at quickening games. Extra innings would now begin with a runner already placed on second base. The batter prior to the one leading off the inning, or his substitute, would be the designated runner. For scoring purposes, he would be deemed to have reached on an error, so if he scored, the run would be unearned on the pitcher’s ledger.

This is a device borrowed from international competition, notably the World Baseball Classic, where runners are placed on first and second starting in the 11th inning. The rule was intended not just to spare fans’ attention spans but to limit strain on pitching staffs with shortened games. The WBC has pitcher-use limits, but the extra-inning rules add another layer of attempted protection.

That motive carries over to the new minor-league rule. The minors today are development grounds for players first and competitions only secondarily. Marathon games that tax and tire pitching rosters disrupt those organizations’ development plans. With the near-universal worry about pitchers’ health nowadays, there’s a strong motivation to avoid such random stresses. The new rule would do this…if it actually does cut the length of extra innings.

Reaction to the new rule has been mixed. Some have embraced the change and its intended purposes; others have scorned it as an aesthetic and practical failure. Josh Timmers of the website Bleed Cubbie Blue has said the strategy in the new extra innings, heavy with sacrifice bunts and intentional walks, makes boring baseball. He also says, from his experiences, the rule hasn’t shortened games after all. To quote him:

Someone with more time and money than I have can go through every minor league extra-inning game from 2017 and 2018 and see if there has been any change in the time, the length or numbers of pitches thrown. I’d be surprised if this rule has made a statistically significant difference, and I wouldn’t be shocked if it has actually lengthened games.

I very likely have more time than Timmers does, though probably not more money. (Unless there are raises in the pipeline at THT. Just wondering.) One out of two is good enough for me, so I ran through all those games to answer his assertion.


It happens I did some work in this area several years ago. When studying marathon games in the majors, and their effect on team performance in the days and weeks afterward, I looked briefly at how quickly extra innings produce a winner. I came up with a stat called rate of resolution, which measured how likely it was that a specific extra inning would be the final one of the game. In the major leagues from 1990 to 2011, that rate was 47.03 percent. (One can take the inverse of this and say that extra innings lasted, on average, 2.126 innings.)

In a subsequent piece, I found a correlation between run environment and rate of resolution. Higher scoring makes it more likely than an extra inning will produce a winner. This ties in with the rule change. Putting a runner on second automatically raises the expected runs in an inning by roughly 0.6 runs and hikes the chance at least one run will score from around 30 percent to around 65 percent.

Put very briefly, when an extra inning fails to produce a winner, most likely it’s because both teams scored zero runs. A runner starting on second dramatically lowers the chance of double zeroes. While it also raises the chance of double ones, it more than makes up for the double-zero drop. At least, that is, the theory.

I must confess that I didn’t examine everything Timmers challenged someone to examine. Game times and pitches thrown, I left alone, concentrating instead on the lengths of games by inning. I also didn’t cover the entirety of the minors but cut things off at A-Ball. Also, since the minor-league schedule isn’t complete, I didn’t look over every 2018 game, though I did cover everything up to August 15.

Those bounds, however, are enough to get a clear answer. Minor-league extra innings may now be duller—that’s an aesthetic judgment better left to the collective judgment of all fans—but they are now definitely shorter.

Even though I had a figure for rate of resolution in the majors, I worked through the minors in 2017 to make sure it was in the same range. It was. For the eight minor league circuits at Advanced-A and above, there were 577 extra-inning games, and their combined rate of resolution was 45.9 percent. The mean length of extras was 2.18 innings.

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Goodbye for now.

The figures for 2018 are very different. Through the games of August 15, there were 635 extra-inning games in the minors from Low-A ball up to Triple-A. (This count includes one game in the South Atlantic League that was suspended and called a tie after one extra inning, plus the Midwest League’s All-Star Game, which went to extras and was decided in one extra inning.) Their combined rate of resolution was 71.3 percent. If you prefer the figures for Advanced-A and up, to match precisely the 2017 data set, the rate of resolution was a near-identical 71.4 percent. The mean length of extras was 1.40 innings.

It is notable how closely the figures for the two years hew to the theoretical numbers. For regular extra innings, I put the chance of a zero-run inning at 70 percent, one run at 20 percent, and two or more runs at 10 percent. For the new extra innings, I considered it a coin flip whether the automatic runner on second would score. This put the chances of both zero-run and one-run innings at 35 percent, with two runs at 20 percent, and three-plus at 10 percent. Working out a rough rate of resolution from these numbers (one that leaves out dwindling probabilities of a match of high-run innings) looks like this:

  • 2017: 1 – [(0.7^2) + (0.2^2)] = 0.47
  • 2018: 1 – [(0.35^2) + (0.35^2) + (0.2^2)] = 0.715

The 45.9 percent rate for the 2017 minors is close to the theoretical 47 percent, and the 2018 rate of 71.3 percent is almost a dead match for the 71.5 percent predicted by the formula. Yogi Berra may or may not have said, “In theory, there’s no difference between theory and practice, but in practice there is.” In this case, however, the difference was so small as not to matter. The games on the field did what they were expected to do. The new rule did what it was expected to do, cutting extra innings by two-thirds of the maximum possible reduction (that being, down to one).

The instance of long extra-inning games has commensurately plummeted. In 2017, the minors from Advanced-A upward had 93 games go into four extra innings or more. This year, through about six-sevenths of the season, the number is 12, pro-rating out to 14 by season’s end. One could scarcely have hoped for a more decisive effect.

I also looked at the relationship between the leagues’ run environments and their rates of resolution this year. I was hoping to see the positive correlation between the two I found in my earlier pieces.

It is there, but only barely. The R^2 is a tiny 0.0355, meaning next to no correlation. I suspect a mere 10 league seasons was not enough for the trend to assert itself. Oh, well; the effects can’t all be stark and obvious.


While it isn’t in the primary scope of this study, I would be remiss if I did not mention a particular Advanced-A game on August 5. The Clearwater Threshers (a Phillies affiliate) and the Tampa Tarpons (a Yankees farm team) almost forced us to confront a paradox: Can you lose a perfect game?

Deivi Garcia of the Tarpons threw perfect baseball through the scheduled seven innings of the game—doubleheader games in the minors are scheduled for seven—but the score was 0-0 in regulation. The Threshers got their automatic runner on second in the top of the eighth, and he scored on an error and a fielder’s choice. Tampa lost 1-0, and while the on-field error ended the perfect game, the Tarpons still had a combined no-hitter even if they didn’t have the win.

But what if there hadn’t been an error? The runner on second could well have scored on two productive outs. Would that, despite losing, still have been a perfect game?

The Tarpon pitchers would not have allowed a batter to reach base, so it would have been. But there was a baserunner in the eighth (reaching on an error, at least for scorekeeping purposes), so it wouldn’t have been. Depending on the definition one applies, it could be either.

There may be an official answer to this, but I’ve decided not to seek it out. The question is really better unresolved, a Zen koan of baseball, inspiring meditation on the nature of the game and all we attach to it.

Still, this is baseball. Anything than can happen on the field eventually will. Assuming the rule remains in force, we will someday get an answer to the koan, somewhere in the minors—or possibly higher.


The experiment, after all, has been a success. It accomplished the stated goals, shortening extra innings and relieving stress on young pitching staffs. This not only makes it highly likely the rule will remain in force in the minor leagues but opens the door a crack to its adoption by the majors.

Commissioner Manfred is not pushing such a move. In statements made before the start of the minor league season, he said, “I don’t see this as a rule that we’re going to bring to Major League Baseball.” He called the extra-inning rule a “good experiment—one that probably is not Major League worthy.”

One can, though, see daylight peeking through those words. “I don’t see this” and “probably is not” are not cast-iron denials. The motives for instituting the rule in the minors-length of games and concern over fatigue and thus injury risk to pitchers-pertain just as well to the majors if not more so. It would upend a great deal of history and continuity in baseball, but Manfred has shown himself willing to make such changes on a smaller scale.

This isn’t to say Manfred has had a nefarious, covert plan to introduce this rule to the majors all along. He simply could see how the experiment worked in the minors and talk himself into something. And he never said “never,” did he?

We fans need to be prepared. Love it or hate it, this rule is no longer unimaginable for Major League Baseball. If you want it, call for it. If you don’t want it, marshal your arguments against it. (My opinion, worth what you’re paying for it, is it’s a bridge much too far, and I might actually prefer letting MLB games end as ties than have them resolved in this artificial manner.)

But for a peek in MLB’s future, you might want to look in at your local minor league park. And not just for the pitch clock.

References and Resources

A writer for The Hardball Times, Shane has been writing about baseball and science fiction since 1997. His stories have been translated into French, Russian and Japanese, and he was nominated for the 2002 Hugo Award.
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5 years ago

Even though I understand the reasoning of the rule-change. I really hope it never reaches MLB. It is perfect for the minors. There should be a push for shorter extra inning games, when the games absolutely don’t matter. The minors are purely for player evaluation and development. There is not much evaluation/development in a 16 inning game.

5 years ago

Just do a freaking draw, of all the possible ideas, this is the stupidest by far.

Da Bear
5 years ago

A more palatable version of this idea, instead of saying “always start with a runner on second”, might be “extra innings start with the same configuration of runners that were left on base from the previous inning”. This would prevent the issue of a team possibly throwing a perfect game and still losing–as long as you retire everyone, you wouldn’t have to worry about these extra runners. On the flip side, if runners do start getting on, the pitcher won’t really be able to “get out of a jam” for long, as that jam will continue to be in place for the next inning, until either the dam breaks and those guys actually come around to score, or if the team can use that brief reprieve to apply enough offensive pressure for one inning to win the game immediately.

Jetsy Extrano
5 years ago
Reply to  Da Bear

I like that. Baseball, with more crushing inexorability of death.

5 years ago

Can you show the winning % of the home team for the new rule extra inning games. I feel there is a huge advantage for the home team. If they can keep the visiting team off the board, they can play for one run all the time. Sac the player to 3rd and another ball in play probably wins the game. If not they go another inning and try again. They have nothing to lose by trying a sac and a squeeze if the other team does not score in their half.

Rich Dunstan
5 years ago

This would be a far bigger change than, say, the DH was, and destructive to basic principles of the game. Getting runners on base is the most important element is scoring runs, and this plan waives that. Da Bear’s idea is somewhat better in that a team would have to get its own runners on base sometime. But anyhow, if we have to have some stunt like this to shorten endless extra inning games, at least save it for the 11th inning and give us one genuine extra inning.