Originally written on Fangraphs  |  Last updated 11/15/14

A few days ago, the San Francisco Giants swept the Detroit Tigers out of the World Series. It was the 21st World Series sweep in history, out of the 108 played since 1903. (The was no World Series in 1904 or 1994.) When the Tigers swept the Yankees, it was the 19th total LCS sweep, out of 86 total since 1969. Obviously, not all playoff series are created equal. Some are best-of-three, like the Division Series, and the LCS between 1969 and 1984. Some are best-of four, like the LCS since 1985, and all but four World Series — the Series was best-of-five in 1903 and between 1919 and 1921. (The Black Sox famously lost the World Series five games to three.) The Wild Card Game obviously isn’t a “series,” nor are the occasional 163rd games played at the end of the season. Since the inauguration of the modern playoff format with the creation of the World Series in 1903, all playoff series have been either best-of-three, -four, or -five, though that was not always the case. The Detroit Wolverines beat the St. Louis Browns 10 games to five in the 1887 World Series; that was not an official championship series, but can you imagine a best-of-19 series? It’s more like a skins golf match than the playoffs. There have been 270 playoff series played since 1903: 108 World Series, 86 League Championship Series, and 76 Division Series, counting the Division Series games played in 1981 following the strike. Naturally, the best-of-threes are the series that are most prone to see a sweep. By my count, the World Series and ALCS sweeps were the 26th and 27th sweeps of a best-of-four series, out of the 158 total best-of-four series ever played. There were no Division Series sweeps in 2011 or 2012, but in 2010, the Phillies swept the Reds and the Yankees swept the Twins, the 40th and 41st sweeps of a best-of-three series out of 108 best-of-three series ever played. Out of all of the best-of-fours, 17% have been sweeps, while 38% of best-of-threes have been sweeps. Requiring just one more win cuts the chance of a sweep in half. The LCS expanded from best-of-three to its current best-of-four format in 1985, and you can see graphically just how sharply the incidence of sweeps dropped: By contrast, the World Series and LCS have had the same format for almost all of their lives, and you can see that sweep incidence is roughly even over the years: None of the four official best-of-five World Series were sweeps, and it’s easy to understand why. Mathematically, sweeps should become exponentially more rare as the number of games you have to win increases. If two teams are perfectly evenly matched, then you would expect that there would only be a 12.5% chance that one would sweep the other in three games, just a 6.25% chance that one would sweep the other in four games, and a 3.1% chance that there would be a sweep in five straight. Even if they’re unevenly matched, you would expect sweeps to be relatively rare. If one team were 70% likely to beat the other in a single game — if, that is, the probability of one team beating the other is 70% — you would only expect a three-game sweep 34% of the time, and a four-game sweep 24% of the time. That’s a large drop, but not as drastic as the 38% to 17% drop that we observed in the data. What accounts for this? Maybe it’s an artifact of small sample size. After all, we only have 270 playoff series to work with. Or perhaps there’s a true all-hands-on-deck effect: maybe managers’ in-series strategy actually changes their teams’ likelihood of winning a game, so that the team that was 70% likely to lose the first game (regardless of matchups) is only 60% likely to lose the fourth game when down 3-0, because they were likely to conserve their effort in the first game but have no incentive to conserve energy in the fourth game. Whatever the reason, the data are clear: it is strikingly easier to get swept in the Division Series than in the League Championship Series or World Series. Losing the first game of the LCS hurts, but it isn’t an existential threat. But losing the first game of the Division puts you on the ropes. Unless, of course, you’re the 2012 Giants, who were down 2-0 in the Division Series and then swept the World Series. It worked for them. But it is likely that we will go a long time until we see that again.

GET THE YARDBARKER APP:
Ios_download En_app_rgb_wo_45
MORE FROM YARDBARKER

Lightning reach Stanley Cup Final with Game 7 win

Devon Still: Daughter has complications with transplant

Rivers denies report of problems with CP3 and Jordan

Orlando Magic hope Skiles can right sinking ship

Falcons waive Shembo over animal cruelty charges

LIKE WHAT YOU SEE?
GET THE DAILY NEWSLETTER:

Report: Tom Brady’s suspension appeal hearing set for June 23

Peterson is wrong (sorta): NFL players have great power

Scout: A-Rod 'looks like he doesn't give a (expletive)'

Belichick mum on Deflategate in first remarks since discipline

Dwight Howard suspended for first game of 2015-16 season

Bucs veterans missing Jameis while he's at rookie symposium

WATCH: Josh Hamilton hits first two homers of the season

Did Andrew Bogut take a shot at Mark Jackson?

$70 million Reebok deal is bad for UFC fighters

If the Warriors win the NBA title, the parade will be for Oakland

SEC no longer allows transfers with 'serious misconduct' issues

Klay Thompson officially diagnosed with concussion

Snoop Dogg hooks Texas A&M up with adidas cleats

WATCH: Stephen Curry rides a mini-horse

Metta World Peace gets ejected after five fouls in one minute

On satellite camps and the SEC crying over its self-protections

Four NFL quarterbacks set to take a step back in 2015

Spelling Bee co-champ wears LeBron jersey under shirt

MLB News
Delivered to your inbox
You'll also receive Yardbarker's daily Top 10, featuring the best sports stories from around the web. Customize your newsletter to get articles on your favorite sports and teams. And the best part? It's free!

By clicking "Sign Me Up", you have read and agreed to the Fox Sports Digital Privacy Policy and Terms of Use. You can opt out at any time. For more information, please see our Privacy Policy.
the YARDBARKER app
Get it now!
Ios_download En_app_rgb_wo_45

Lightning reach Stanley Cup Final with Game 7 win

Devon Still's daughter has complications with transplant

$70M Reebok deal is bad for UFC fighters

If the Warriors win the title, the parade will be for Oakland

Peterson is wrong (sorta): NFL players have great power

Dwight Howard suspended for first game of 2015-16 season

Four QBs set to take step back in 2015

Spelling Bee co-champ wears LeBron jersey under shirt

Top 10 stories from 2015 NBA Playoffs

Rangers-Lightning Game 7 preview

The can't-miss Prince Fielder

Chip Kelly: Tebow is a quarterback

Today's Best Stuff
For Bloggers

Join the Yardbarker Network for more promotion, traffic, and money.

Company Info
Help
What is Yardbarker?

Yardbarker is the largest network of sports blogs and pro athlete blogs on the web. This site is the hub of the Yardbarker Network, where our editors and algorithms curate the best sports content from our network and beyond.