Seems like whenever I'm in a league where a team with a dominant regular season record loses to a team with a much weaker record, there is endless ******** and moaning about how unrealistic WIS is, how "this always happens" etc.

Well, I have no idea, and am far too lazy, to want to count the results of every postseason series from every WIS league I'm in, but using www.baseball-reference.com, it's pretty quick and easy to figure out how often this happens in real MLB.

I went back to 1995, the first year of the LDS.  From 1995 through 2012 there have been 126 postseason series.  I am not counting play-in games or the 1-game Wild Card games from 2012.  Just LDS, LCS, and World Series.

In 5 of those series, the two teams had the same number of wins (I only looked at wins, though because of strikes, rainouts, etc it's possible that 2 teams with the same number of wins did not have the same record.)

Of the 121 series in which 1 team had more wins than the other, there were 23 series in which the difference was 11 wins or more.  The "better" team (ie the team with more regular season wins) won 14 of those 23 series (60.9%).  Put differently, 40% of the time, a team with a much worse regular season record wins a playoff series against a perceived stronger opponent. 

The biggest of these upsets was of course the 2001 Yankees (95 wins) beating the Mariners (116 wins).  But other notable upsets include the 2006 Cardinals (who pulled the trick twice, over the Mets and the Tigers), and the 2003 Bartman Cubs (88 wins) who beat Atlanta (101 wins) in the LDS.

I think that's pretty noteworthy....40% of the time the lesser team wins in MLB even when the disparity in records in huge.  If we went back and included all postseason series in MLB history, I don't know if the numbers would change overall, but we would get interest examples like the 1906 Cubs and 1954 Indians, two teams that were defeated by clubs with much poorer records.

But perhaps more interestingly...in the 98 series in which the win-difference was 10 wins or fewer, the "better" team won 49 series.  Exactly half the time.  Basically, when two teams are within 10 wins of each other in MLB, there is no statistical difference between them in terms of post season outcomes. 

We can parse these results further...when the difference is 5 wins or fewer the "better" team won 29 of 61 series (47.5%) and when the difference is between 6 and 10 wins, the "better" team won 20 of 37 series (54.1%).  I didn't check, but I would shocked if either result is statistically significant.

Upsets happen all the time in major league baseball, and in general even a 162 game season is not enough to differentiate the quality of 2 teams unless the win differential is huge.

This post should be required reading for newbies.

regular season records are not always a good indicator of which team will probably win a playoff series

Good read Contrarian.  Thanks for doing the research.  I learned something from your post. 

hah!

Good post contrarian. Interesting results. I see I said about the same thing five years ago. Had forgotten the results so it is good to be refreshed.

2019 Bump.

From 1995 through 2018, there were 162 postseason series (best of 5 or 7) in which the two teams had different records (more precisely, different number of wins). 75 out of 162 (46%) the team with fewer regular season wins ended up winning the series.

There were 38 series in which one team had a 10+ win advantage. In 15 of those series (39%), the team with fewer regular season wins ended up winning the series.

Just something to keep in mind the next time a WIS owner moans about how their top-seeded team always seems to lose in the first round of the playoffs....

I’m sure you’ll be happy to do the legwork on that for us, right?

My point is that it is not remotely an unusual occurrence in MLB. To hear some WIS owners tell it, you would think such an upset would be rarer than a truthful statement coming out of Trump’s mouth.