I’ll admit to being a Liberty HS (Issaquah) girls basketball fan. Long ago, although I can remember, when Liberty made the state tournament in 1999, they played their winner-to-state versus Hazen, the next high school over.
Now Hazen finished second in Seamount that season, which doesn’t sound so bad. In the district tournament they played Holy Names, considered one of the hot teams in the state that season. Holy Names was Metro #1 and Hazen was Semount #2. Hazen won. “What a huge upset!” was my thought. But other than my opinion that Seamount girls basketball was mostly crappy and Metro mostly not (at least in the top half of the league) I had meager data to back it up. I needed to formulate criterion to determine what constituted an upset.
It took nearly fifteen seasons and acquisition of lots of data that I didn’t have in 1999, but I came up the the TeamBrunnhilde points rating, calculated historically now from 1988-1989 on. Using the TB Points rating calculated after the season, one can determine what games were won by teams with lower ratings. These can be classified as ‘upsets’.
Not every such ‘upset’ is much of a surprise, however. If Richard Nixon high school has a 23.80 points rating, and Lance Armstrong high school is rated 23.77, is an Armstrong win over Nixon an upset? Technically, yes, but practically, no. One would say Nixon and Armstrong were pretty well matched. But the points rating, shown to have a track record better than most for picking winners in state games correctly, is a reasonable start to assess upset magnitude.
Nowadays, when I attend a game, I consult my TB Points rating to estimate the final margin (point spread for when betting on girls’ high school games is legalized). What does that mean if Richard Nixon HS is rated +7.83 over Harvey Weinstein HS? How likely is Nixon to kick Weinstein’s ass? Or just win?
So I looked at my database for girls’ games 1988-2017 (as of October 10, 2017). In all, I’ve recorded 103,779 girls’ game results where I have ratings for both teams. The lower rated team won 14.07% of those games. Upsets if you will. However, most of those upsets occurred at fairly low ratings differences. For very closely rated games (ratings differences less that 1 point), the lower rated team won 46.97% of the time. Out of 4245 games, that beats flipping a coin. Not until one gets to about a 12 point difference does the upset percentage drop to 10%. That is for games with TB Points ratings differences of between 11 and 12 points, the lower rated team wins 10.79% of the time.
The biggest upset was Thorp over Waterville on January 26, 2001. Waterville was a 52.72 point favorite, but lost 32-26. But that Thorp Waterville upset is suspect since Waterville may have counted it as JV and not brought their best team. Waterville had too many games: two late season non-league games (including that one) do not appear in their State Tournament program game listing. (Disclaimer added after initial post).
Upsets with TB Points differences over 30 are quite rare. Of 15,487 such games only eight times was an upset recorded. Better odds than PowerBall, though.
For playoff games, the percentage of upsets is higher, 19.80% of 14,968 games. But that is mostly due to the worst teams getting eliminated quickly, leaving more closely matched games as the tournaments progress. For instance, for all games 79.43% of the games have TB Points rating differences of 26 points or less. For Playoff games 92.38% games are under 26 points. To get under 80% for playoff games, the TB Point margin drops to 17. The actual rate of upsets for various margins is roughly equivalent. The biggest playoff upset was Lopez over Neah Bay on February 18, 2011. Lopez, a 24.88 point underdog won 45-33.
Oh yeah. Hazen was a 22.8 point underdog when it beat Holy Names in 1999: the fifth biggest girls’ playoff upset in my database.
Following is the summary for upsets in games based on the differences of end-of-season TB points rating (so it may not agree with a similar analysis taken of differences during the season). The first column indicates the difference between the two teams point rating (stated in absolute terms). One can see in the last column the percentage of games where the lower rated won steadily decreases, until the ‘rare random event’ portion of the distribution takes over. Girls’ data 1988-2017.
|
range |
All Games |
||
|
upsets |
games |
||
|
[0,100) |
14603 |
103779 |
14.07% |
|
[0,1) |
1994 |
4245 |
46.97% |
|
[1,2) |
1899 |
4195 |
45.27% |
|
[2,3) |
1680 |
4271 |
39.34% |
|
[3,4) |
1456 |
4115 |
35.38% |
|
[4,5) |
1270 |
4041 |
31.43% |
|
[5,6) |
1096 |
4019 |
27.27% |
|
[6,7) |
963 |
3937 |
24.46% |
|
[7,8) |
810 |
3894 |
20.80% |
|
[8,9) |
657 |
3642 |
18.04% |
|
[9,10) |
560 |
3745 |
14.95% |
|
[10,11) |
471 |
3769 |
12.50% |
|
[11,12) |
368 |
3410 |
10.79% |
|
[12,13) |
294 |
3323 |
8.85% |
|
[13,14) |
226 |
3162 |
7.15% |
|
[14,15) |
206 |
2979 |
6.92% |
|
[15,16) |
155 |
2874 |
5.39% |
|
[16,17) |
117 |
2806 |
4.17% |
|
[17,18) |
96 |
2726 |
3.52% |
|
[18,19) |
88 |
2513 |
3.50% |
|
[19,20) |
55 |
2466 |
2.23% |
|
[20,21) |
40 |
2409 |
1.66% |
|
[21,22) |
23 |
2133 |
1.08% |
|
[22,23) |
22 |
2083 |
1.06% |
|
[23,24) |
14 |
2036 |
0.69% |
|
[24,25) |
15 |
1811 |
0.83% |
|
[25,26) |
6 |
1827 |
0.33% |
|
[26,27) |
8 |
1609 |
0.50% |
|
[27,28) |
4 |
1471 |
0.27% |
|
[28,29) |
2 |
1438 |
0.14% |
|
[29,30) |
0 |
1343 |
0.00% |
|
[30,31) |
1 |
1282 |
0.08% |
|
[31,32) |
0 |
1186 |
0.00% |
|
[32,33) |
2 |
1087 |
0.18% |
|
[33,34) |
0 |
1068 |
0.00% |
|
[34,35) |
1 |
960 |
0.10% |
|
[35,36) |
0 |
903 |
0.00% |
|
[36,37) |
0 |
844 |
0.00% |
|
[37,38) |
1 |
678 |
0.15% |
|
[38,39) |
2 |
696 |
0.29% |
|
[39,40) |
0 |
591 |
0.00% |
|
[40,41) |
0 |
618 |
0.00% |
|
[41,42) |
0 |
495 |
0.00% |
|
[42,43) |
0 |
550 |
0.00% |
|
[43,44) |
0 |
482 |
0.00% |
|
[44,45) |
0 |
430 |
0.00% |
|
[45,46) |
0 |
380 |
0.00% |
|
[46,47) |
0 |
341 |
0.00% |
|
[47,48) |
0 |
297 |
0.00% |
|
[48,49) |
0 |
287 |
0.00% |
|
[49,50) |
0 |
252 |
0.00% |
|
[50,51) |
0 |
244 |
0.00% |
|
[51,52) |
0 |
195 |
0.00% |
|
[52,53) |
1 |
179 |
0.56% |
|
[53,54) |
0 |
160 |
0.00% |
|
[54,55) |
0 |
140 |
0.00% |
|
[55,56) |
0 |
106 |
0.00% |
|
[56,57) |
0 |
116 |
0.00% |
|
[57,58) |
0 |
102 |
0.00% |
|
[58,59) |
0 |
91 |
0.00% |
|
[59,60) |
0 |
99 |
0.00% |
|
[60,61) |
0 |
111 |
0.00% |
|
[61,62) |
0 |
67 |
0.00% |
|
[62,63) |
0 |
72 |
0.00% |
|
[63,64) |
0 |
47 |
0.00% |
|
[64,65) |
0 |
55 |
0.00% |
|
[65,66) |
0 |
42 |
0.00% |
|
[66,67) |
0 |
28 |
0.00% |
|
[67,68) |
0 |
27 |
0.00% |
|
[68,69) |
0 |
26 |
0.00% |
|
[69,70) |
0 |
23 |
0.00% |
|
[70,71) |
0 |
20 |
0.00% |
|
[71,72) |
0 |
17 |
0.00% |
|
[72,73) |
0 |
17 |
0.00% |
|
[73,74) |
0 |
4 |
0.00% |
|
[74,75) |
0 |
14 |
0.00% |
|
[75,76) |
0 |
11 |
0.00% |
|
[76,77) |
0 |
10 |
0.00% |
|
[77,78) |
0 |
7 |
0.00% |
|
[78,79) |
0 |
4 |
0.00% |
|
[79,80) |
0 |
4 |
0.00% |
|
[80,81) |
0 |
2 |
0.00% |
|
[81,82) |
0 |
4 |
0.00% |
|
[82,83) |
0 |
2 |
0.00% |
|
[83,84) |
0 |
3 |
0.00% |
|
[84,85) |
0 |
2 |
0.00% |
|
[85,86) |
0 |
0 |
0.00% |
|
[86,87) |
0 |
0 |
0.00% |
|
[87,88) |
0 |
3 |
0.00% |
|
[88,89) |
0 |
0 |
0.00% |
|
[89,90) |
0 |
0 |
0.00% |
|
[90,91) |
0 |
3 |
0.00% |
|
[91,92) |
0 |
1 |
0.00% |
|
[92,93) |
0 |
0 |
0.00% |
|
[93,94) |
0 |
0 |
0.00% |
|
[94,95) |
0 |
1 |
0.00% |
|
[95,96) |
0 |
0 |
0.00% |
|
[96,97) |
0 |
1 |
0.00% |
|
[97,98) |
0 |
0 |
0.00% |
|
[98,99) |
0 |
0 |
0.00% |
|
[99,100) |
0 |
0 |
0.00% |