Sumo as Science: Yoshikaze’s History as M2

Hmmm… the basho still hasn’t started.  While waiting, I thought I would just see what happens if I calculated DoS for Yoshikaze during his three previous performances at M2.  I’ll tell you what… the results aren’t pretty.  During Yoshikaze’s first time as M2, he faced so many rikishi for the first time and he had so many short histories with other rikishi that I thought I needed to indicate this on the Moneyshot Score Sheet. So, I put a * next to all the DoS scores for rikishi that Yoshikaze was facing for the first time, and I put a + next to all the DoS scores for rikishi that Yoshikaze had a short bout history with.  As you can see on the charts below, one of these symbols appeared on almost every bout he fought.

I think Yoshikaze’s first performance at M2 really shows the limitations of the DoS score.  It really wasn’t a very good reading.  His DoS score ended up being way lower than later performances against those same rikishi showed it should have been.  However, I do think that newbie rikishi have a bit of an advantage the first time they face the big guys because they are a bit of an unknown quantity.  What do you all think?  

Now, as you can see, Yoshikaze is not exactly the story of a rikishi who is getting better and better.  It will be interesting to see how he does this basho, but based on the direction of his DoS scores, I am certainly not going to be predicting that he will do well at M2 this time around.

I guess its time to stop and reflect a bit on the DoS score.  It seems to be telling us the obvious.  That is both good and bad.  Its good because it means that it is, to at least some degree, an accurate measure of difficulty of schedule.  Its bad because it does take a bit of effort to calculate, and if it only tells us what we already know, then… maybe its not worth much…

However, I think calculating the DoS score does have some benefits.  First, for anyone new to Sumo, it is going to give you a good sense of bout histories.  By keeping track of the DoS score, you should find out a lot about how your rikishi stands in comparison to the rikishi he faces.  Well, I guess we will see how it goes.

Enough chatter:  here are the charts:




9 responses to “Sumo as Science: Yoshikaze’s History as M2

  1. Here is an alternative…..

    Yoshikaze in Hatsu 2009 could have scored 37.25 given the difficulty of his schedule. If we score only his wins (your heading on the chart is mis-labeled) he got 16.42 (the unexpected win over Futeno on Day 13 really helps him here). So for Hatsu 2009 his Moneyshot score is (16.42/37.25 x 100) 44.08%.

    At the same Basho Harumafuji (using your sheet) could have scored 24.5. If we score only his wins he got 12.00 which equals 48.98%.

    Thus (given the respective difficulties of their schedules) Harumafuji performed 4.90% better. Such are the margins of victory.

    Just an idle thought.

  2. Hajinochikara

    I like this idea. I’ll explore this idea a bit tonight and then see how people feel about using it for Moneyshot this basho. Does anyone have any requests for rikishi they would like to see featured in the next Sumo as Science post?

    (nice catch on the heading… I missed that when I revised from an earlier draft of the Scoresheet).

  3. Hajinochikara

    I just had a thought – I am not sure we should divide by the overall cumulative DoS.

    Consider a hypothetical case where one rikishi faces opponents with a DoS of 1 each and a second rikishi faces opponents with a DoS of 5 each.

    Rikishi 1 wins all 15 bouts and gets a Difficulty of Win score of 15.

    Rikishi 2 wins 3 bouts and gets a Difficulty of Win score of 15.

    In this case the Margin of Victory for Rikishi 1 over Rikishi 2 would be 80%.

    I think the more accurate measure to compare to rikishi performance over a basho is just the Difficulty of Win score you came up (I don’t think there is any need to divide by the overall cumulative DoS).

    This would be to say that Rikishi 1 (with his fifteen easy wins and his Difficulty of Win score of 15) had a comparable performance to Rikishi 2 (with his three extremely difficult wins and his Difficulty of Win score of 15).

  4. Sadly I`m not a statistician 🙂

    The reason I thought comparing how well each rikishi had performed (against the difficulty of his individual schedule) in percentage terms (dividing by overall cumulative DoS) was because (in the example I used) Harumafuji could have gone Zensho-Yusho, scored 24.50 DoS points and still have lost to Yoshikaze. That didn`t seem quite fair.

    But I`m perfectly happy to go with adding up the wins. It will be interesting at the end of the Basho to see how the Moneyshot Rikishi rank (highest to lowest) in terms of DoS points.

    Theoretically the highest DoS-point-scorer should also be the Shakun-Sho winner!

  5. Hajinochikara

    But Haruma wouldn’t have lost to Yoshi in that case. Yoshi got 16.42 win points. If Haruma had gone Zensho, he would have gotten 24.5 win points and won.

    However, I see your point. If Yoshi had gotten 25 of his 37.25 possible win points, he would have beaten out Haruma, even if Haruma had gone Zensho.

    I think this ok, though. Part of the reason I came up with Moneyshot in the first place is because it is (was) so boring to see Hakuho go Zensho (or very near to Zensho) every single basho. Moneyshot is intended to make a yusho race by adding in DoS (for Hakuho, zensho is easy, for Haruma zensho is harder, so if they both go zensho, Haruma wins).

    Adding in DoS is kind of like putting a handicap on the best players to level the playing field and make the competition more interesting. We all know that Hakuho is the best player, and that Haruma is a better rikishi than Yoshikaze, so Moneyshot isn’t looking at overall skill. Instead, Moneyshot is meant to focus on rikishi who have a great basho.

    So, lets say that Yoshi gets his 25 win points and Haruma gets his zensho. Even without Moneyshot, we are all going to be super excited about Haruma’s zensho, but without Moneyshot, we might not even have noticed Yoshi.

    “Leveling the playing field” is definitely unfair because we are trying to put less skilled rikishi on the same level as more skilled rikishi so that we can compare performance across skill levels. Really, we aren’t leveling the playing field so much as unlevelling it, come to think of it.

    But, I think it will make for more interesting sumo viewing even if it is unfair.

    I’m thinking about your idea of dividing the win points by the cumulative DoS (even though I really should be doing other things). I think that idea is a very fair way to evaluate rikishi performance at rank. So if we want to know if Yoshikaze is more deserving of the M2 rank in Hatsu 2009, Hatsu 2011 or Aki 2011, your idea would be perfect. I am not sure if this is quite the right way to think about it or not, but if we say that 50% means that the rikishi is exactly deseriving of the rank, then Yoshi would…

    Hatsu 2009: 44.1%
    Hatsu 2011: 19.4%
    Aki 2011: 33.4%

    …not deserve the rank any of the three times he earned (and this is true as he was demoted after all three times).

    That first time at rank is probably a bit of an oddball, but it does seem like Yoshi got better from Hatsu 2011 to Aki 2011 (either that or else the ranks of Sumo as a whole got worse – usually that wouldn’t be likely, but given the kind of year that 2011 was…)

  6. “without Moneyshot, we might not even have noticed Yoshi.”

    The best of all possible reasons to play this game. And, yes, 2011 was a Suntory year 🙂 Treat yourself to a bottle of Talisker this time around!

  7. Hajinochikara

    Definitely true. In a world where Sumo was in a better place, there would be no need for Moneyshot. As things are though… hopefully this game will liven up the basho and give us something to think about other than how much it sucks that the top guys are playing funky sumo.

  8. Pingback: Sumo as Science: Hakuho and Asashoryu | Sumo & Stogies

  9. Pingback: Sumo as Science: Summary | Sumo & Stogies

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