The Biggest Upsets In SCII History
2021/04/23: Article updated to include a breakdown of upsets by year
After the recent upset in the NeXT 2021 S1–SC2 Masters EU qualifiers, many people including myself were wondering if there had ever been a more unexpected results to any professional game of SCII. After all 2077 Aligulac rating points separated Hyperion and Reynor, and Aligulac had given Hyperion less than a quarter of a percent of a chance of winning the bo3.
The game in question
There was a pretty straightforward way of determining if this was the biggest upset ever, so I downloaded aligulac (from http://aligulac.com/about/db/. And as always thank you to all aligulac contributors and maintainers for keeping up to date such a great tool), did some querying, and here are the results. I do have to note that Aligulac ratings are fairly inflationary, so the unadjusted results will be biased towards more recent results. As such almost all of the following rating unadjusted upsets happened in LotV.
And it goes without saying that all these players getting upset are incredibly good--the only reason that it's such an upset/achievement to beat them is that they are so good.
The first thing I noticed is that a few of these 'biggest upsets' were due to progamers offracing, and should be excluded from contention. Kudos anyways to the underdogs, since these are some big upsets, but the progamers were operating under a pretty severe handicap.
I also didn't want to include Bo1s in the final list since Bo1s are quite volatile comparatively. Here are the biggest Bo1 upsets.
There are some interesting examples here. In the case of Ptak he played the greatest Starcraft of his life that day. He beat both GSL champions ByuN and Zest during the Nation Wars IV qualifier (beating Zest was "only" a 915 rating point upset) before barely losing to INnoVation.
In the case of Hellraiser and Spatz who beat Nerchio and Reynor respectively it can be argued that they were very underrated at the time, or that their rating was still busy catching up to their rapidly improving skill. Future similarly beat GuMiho when he was only rated 1139 for a 1322 point upset.
I also did some filtering to see if there was anything to be found from some subsets of these upsets. Here are the biggest Bo5+ upsets:
These have comparatively smaller upsets, since there are far fewer Bo5s than Bo3s. MCanning defeating Neeb was quite notable though.
And here are the offline Bo3 upsets:
MeomaikA beating Maru at WESG stands out as the most notable of these results.
And here are the greatest upsets of all SCII:
As it turns out Hyperion beating Reynor is the biggest upset of all and it isn't even close. It's the only 2000 point upset with no other result coming close. Even if we include the Bo1s and the progamers offracing there isn't a result that comes within 300 points of it.
Hyperion vs Reynor had the most surprising outcome ever.
[UPDATE] Upsets adjusted for rating and broken down by year
By request I did some extra investigation into what upsets happened in the early years of SCII, and tried to account for Aligulac's rating inflation. During this extra research I found that I'd previously missed a few upsets since I'd been sorting by the difference in rating rather than the difference in per-matchup rating for the relevant rating--this didn't change any of the top upsets, but it does mean that LambNRice defeating souL slips in in 9th place for example.
As it turns out that Aligulac ratings in 2010 and 2011 are not particularly useful. Ratings simply hadn't had the time to settle, which means the biggest upsets were... rather strange.
In 2010 all the top upsets are just good players who were drastically underrated beating MorroW who was the highest rated player in the world at the time. In 2011 all the top upsets are basically just Nerchio's worse go4sc2 defeat--back then he was rated very highly and played a ton of games against much lower rated opponents (unlike most of the other top rated players).
Things start looking much more reasonable in 2012:
Honorable mentions to Forsen beating PuMa (882 points) and Nerchio (792 points), Ziktomini beating Stephano (799 points), and especially TriMaster beating Marineking (886 points) at MLG which I remember watching live.
KingKong is a bit of a strange case where his Aligulac rating was rather inflated from playing in SEA. And the most high profile upset of 2013, Sjow vs Life had a difference of 825 rating and so misses out from the top 5 but not by a lot.
I don't have much to say about the remaining years of upsets as many of them were already featured before the update.
Cell really impresses by having the top upset in two consecutive years.
Spy's quite young, so maybe a player to look out for in the future?
The question of how to best adjust the ratings to account for rating inflation was probably the most subjective part of this entire exercise. I ended up deciding to weigh by the rating of the 10th best player from the previous aligulac period. The reason I chose the 10th best player is that using the best player alone added quite a bit of volatility--whereas the 10th best player is usually not too far from the 9th and 11th best and as such a better way to measure rating inflation. I considered also weighing by the difference between the 10th best and 10th worst player since after all ratings have deflated a bit on the far end of the bell curve. In the end I didn't do that, since that turned out to inflate old results excessively. I think that's because the starting rating for a new player stays the same, so we don't want to double-count inflation. Additionally I didn't include results from 2010 and 2011, because of the issues mentioned above--ratings were a bit all over the place back then, and inflation was really crazy which makes adjusting for it even harder.
Using this I obtained this list of the "Greatest Upset of All Time (Rating Adjusted)" I do think it still might lean a bit towards recent results, but that's hard to say.
"Hyperion vs Reynor" is still the biggest upset, but there's a decent inflation-related argument to be made for "Cell vs Maru" and "Nefaste vs Soulkey" too.