It was September 6th, 2017. The Diamondbacks completed a sweep of the Dodgers in Los Angeles with a 3-1 victory, Taijuan Walker getting the win and Adam Rosales hitting a go-ahead double in the seventh inning. It was, remarkably, Arizona thirteenth victory in a row, a franchise record which still stands. But what’s more remarkable is that, in the close to nine years since that date, the D-backs have not had a winning streak which has reached half of that length. Yes: that was the last time Arizona won
more than a very modest winning streak of six games in a row. Indeed, it has now been more than two years since they even reached that, in late August 2024.
Seven-game winning streaks are not exactly rare. On the same day the D-backs won their 13th and final contest, they were one of three teams with an active 7+ game winning streak. The Astros racked up their seventh win that day, and the Cleveland Indians were winning their 14th in a row. They were on the way to a winning streak which would end at a staggering twenty-two games, the longest of any team in the live ball era. Fun fact: that was the only date in recorded baseball history, that two teams have simultaneously been on winning streaks of thirteen games or more.
The great drought
Between then and the end of 2017, the Athletics and Cubs would also post seven wins in a row. Every other team in the majors would follow suit. Since the end of the D-backs last such streak, there have been no fewer than 206 times where a team has gone seven or more unbeaten. It’s just that none of them are by Arizona. The chart below shows the number of 7+ game winning streaks for each team since the start of 2018 (203 in all).
The two branches of the Evil Empire, on the East and West coasts, have each got to enjoy no fewer than eighteen separate winning streaks of 7+ games, since the last time the Diamondbacks had one. The sense of entitlement is strong. I mean, it makes sense in that, at the time of writing, the only team to have won more games than the Yankees are the Dodgers. Most of the teams high up the chart above are similarly high up the overall win rankings from 2018-26. The most obvious exception are the Red Sox, who rank =3rd for win streaks, but only come in ninth for overall wins.
On that basis, the D-backs do have good reason to feel hard done by. They rank 18th in wins, and a similar position for win streaks would have given them five over the past nine seasons, rather than zero. I mean, hell, even the Colorado Rockies – dead last in wins, by twenty, over this time-frame – have enjoyed a pair of seven-game streaks, and a pair of eight-game streaks. You would think Arizona would have simply lucked into a lengthy winning streak, just by chance. I mean, we’re talking over 640 wins. You would think they might have bunched together at some point in nine years.
What are the odds?
It’s actually a non-trivial task to figure this out. [Those who are not a mathematical bent might care to skip this section, or at least scroll down to the conclusion, which I’ll put in bold] If you know the chances of winning a single game, it’s quite easy to calculate the basic odds of winning seven in a row. x^7, where x is the chance of winning a single game. This presumes the odds are the same for each game, but if we go down the rabbit-hole of figuring out different probabilities for each contest, we’ll never get anywhere. However, if you are looking for the odds of a 7-game streak over a season, things get complex, but results are no longer independent.
For a single baseball season, there are 156 different points at which a seven-game streak could start. If you reach game 156 without one and lose, there’s not enough time thereafter for such a streak. But they overlap: a single loss in, say, game 100, will eliminate streak #94 through #100 from consideration. So it gets complex. If you should be interested, The Hardball Times has all the information you could possibly want, in their 2019 article called The Probability of Streaks. Though it’s too much math, even for me.
Should we treat each season as separate. Does winning the last three games then the first four the next year count? Not that the answer either way would help the D-backs. At this point, heading towards a decade, I would take any good, long winning streak. But let’s start with the odds of a .500 team winning seven in a row, within a single season. Google AI does a good job of explaining the math, involving Markov chains and recursion. Turns out an average team has about an average chance – 47% – of a seven-game winning streak in a season. For better teams, the odds are higher. A .550 team has around a 68% shot. Conversely, a .450 team has only a 28% chance.
Now, for the D-backs. They have played 1,357 games since the last time they won seven in a row, going 656-701 for a win percentage in that time of .483. The math tells us there is a 98.79% chance a seven-game winning streak would happen at least once, so the odds of Arizona avoiding it entirely, as has actually happened, is just 1.21% – roughly a one in 83 chance. Heck, there’s a better than 60% chance of a 10-game win streak. We can also calculate that the a team with that win percentage would be expected to have enjoyed 4.28 separate winning streaks of seven or more games over that span, rather than the zero which have actually happened.
So close, and yet…
While it hasn’t happened for a while, the Diamondbacks have been on the edge of a seven-game winning streak on multiple occasions. Appropriately enough, they have had seven six-game winning streaks, only to go 0-7 when they attempted to win a seventh game. What’s the closest they’ve come? Here are the seven games which ended the six-game streaks:
- Sept 1, 2019 – 3-4 vs. LAD. This defeat was particularly annoying, because the D-backs would go on to win the next five games in a row. Had they prevailed here, it would have given them a 12-game streak. They led 3-2 in the ninth inning, but Cody Bellinger hit a home-run off Andrew Chafin, and we lost in 11 innings. Peak WP: 91%
- Aug 19, 2020 – 1-4 @ OAK. Having skunked the A’s 10-1 the previous day at Chase, as part of a home-and-home series, hopes were high. But Merrill Kelly gave up two runs in the first inning, and two more in the third. The D-backs never threatened, and this kicked off an 8-game losing streak for Arizona. Peak WP: 50%
- June 3, 2023 – 2-5 vs. ATL. The Diamondbacks had squeaked out a one-run win to take the series opener, but the Braves chipped away at Ryne Nelson, with single runs in the third, fourth and fifth innings, building a lead which couldn’t be overcome, while Spencer Strider held Arizona to three hits over his six frames. Peak WP: 61%
- June 13, 2023 – 3-15 vs. PHI. Arizona quickly got back on the horse, and a 5-0 road trip through Washington and Detroit, was followed by a 9-8 win against the Phillies at Chase, rallying from 5-1 down. The next day though.. Zach Davies gave up four runs in the first, and it went downhill from there. Josh Rojas pitched the ninth. Peak WP: 50%
- Aug 26, 2023 – 7-8 vs. CIN, The third streak of 2023 begin with a double-header sweep in San Diego, and die as Arizona couldn’t keep a late lead. They were 4-1 up with two outs in the eighth, and still had a two-run lead with one out in the ninth, but Paul Sewald – remember him? – was unable to hold it. The Reds prevailed in 11. Peak WP: 95%
- Aug 16, 2024 – 4-5 @ TBR. Live by the walk-off, die by the walk-off. The six games leading up to this had seen Arizona walk off against both Philadelphia and Colorado. But they were on the other side of it in Tampa. The D-backs scored two in the ninth to tie the game, but an ugly Jake McCarthy error let the Rays win. Peak WP: 79%
- Aug 27, 2024 – 3-8 vs NYM. There was another six-game winning streak later in the month, starting immediately after the D-backs were swept by the Rays. Impressively all six victories came on the road, sweeping Miami and Boston. But a six-run fifth off Brandon Pfaadt ended all hopes of making it to seven. Peak WP: 50%
So it has been more than two years, and 334 games since the last of these, with a .503 W%. Even the lack of a six-game streak in that time is quite unlikely, with a 94% chance of one showing up. It’s worth noting that since the end of 2017, the D-backs have had about what would be expected in terms of losing streaks of seven or more. There have been six of those, peaking with those terrible, seventeen consecutive losses in June 2020.
I guess all of the above could make you think that the D-backs are overdue, though that feels like a classic example of the gambler’s fallacy. But with the team currently in a dog-fight (albeit one feeling of the “Pekinese vs. Chihuahua” variety!) with the Padres for a wild-card, there’s no denying this month would be a particularly good time for the streakless streak to end.
