How Mima Ito Defeated Hina Hayata At WTT Doha: A Statistical Analysis Revisited
Not the post you were looking for? A guide to all of Edges and Nets’ coverage of WTT Doha (also known as WTT Middle East Hub and formerly known as ITTF Qatar Open) can be found here.
Mima Ito defeated Hina Hayata in the finals 4-2 to win the WTT Contender title at WTT Doha. Before the finals started, Edges and Nets wrote a preview that incorporated rudimentary statistical analysis to verify and draw further insights regarding some of our qualitative observations of Ito and Hayata’s match-up at the All Japan National Championships in January.
In this post we revisit the trends we observed in our preview and discuss whether these trends continued to hold in the WTT Contender finals. For a (non-statistical) summary of the finals, please read our recap here. The statistical trends in this match turned out to vary wildly from the All Japan National Championships match. Although this disparity can be partially attributed to uninformative noise present in small sample sizes, we believe that it also partially reflects the dynamic nature of table tennis and how adjustments between matches and even games can wildly swing the nature of a match.
Disentangling these two factors of variation (statistical noise and change in strategy) is an open problem that Edges and Nets is actively exploring. Any suggestions or feedback is welcome.
Ito Dominates On The Third Ball
In our previous post, we noted that Ito had a massive edge in the long rallies, winning a staggering 71% of rallies in which she attempted four or more shots including all six rallies where she attempted five or more shots in the All Japan National Championships match.
Although Ito’s share of total points won rose from 48% to 54%, this time around, Ito only won fifty percent of the long rallies. However, we believe that this discrepancy from Japan can be mainly attributed to the tiny sample size. The number of long rallies dropped by a fair amount; in Japan 14% of the points (for a total of 17 long points) were long rallies and in Qatar that number dropped to 9% (for a total of 10 long points). Hence, if just one or two points had swung the other way (and a couple of the “long rallies” had a fair amount of pushing), the numbers would look more consistent with their Japan match-up.
Unless Hayata suddenly got better at long rallies or Ito suddenly got worse (which is possible if she had a bad night of sleep or something), it is likely that the odds of Ito’s winning a long rally will have stayed relatively similar between January and now. Combining the results of the two recent match-ups, Ito has won 63% of her 27 long rallies against Hayata over the last two months. Our sample size is still quite small and this number may change even more in the future; however, we still feel that Mima Ito is a stronger player in the rallies from watching them play, and physically her lower body looks quite clearly stronger than Hayata’s.
While the change in percentage of long points won by Ito can be attributed to noise and it is possible that the drop in the number of long rallies can as well, we believe that the drop in number of long rallies is due to change in tactics by the players. First, the sample size is larger and thus more robust as the match had 113 points in total. Second, the number of 5-shot, 4-shot, 3-shot, and 2-shot points all decreased and the average rally length (as measured in Mima Ito shot attempts) dropped from 2.3 to 2. As a result the percentage of “one-shot” points that ended in serve, serve return, or third-ball winner by either player rose from 41% to 50%.
Although we previously stated that it may be in Hayata’s interests to lower the length of the rallies, when watching the match it actually felt like Ito was the main one responsible for shortening the rallies as she attempted difficult and aggressive shots with wide angles. This may be reflected in the change in percentage of “one-shot” points won by each player: in their previous match-up in Japan, Ito only won 47% of such points; this time that number jumped to 59%, indicating that she benefited from the shortened points.
Hayata’s Long Serve Management
In an interesting twist, Ito only won 48% of the points in which she served but Hayata only won 40%(!) of the points in which she served. We are not sure what caused this counter-intuitive result.
In our previous post we speculated that Hayata would consider serving more long serves since she actually performed better on her long serves compared to her short serves. It appears Hayata agreed as her percentage of long serves rose from one third to 46%. Her long serves, of which she won 42%, performed slightly better (albeit within the margin of statistical error) than her short serves, of which she only won 39%. Hence, although our judgement must be taken with a massive grain of salt due to small sample size, it appears that Hayata made the correct choice by serving long more often.
We raised the question if it was beneficial for Ito to step around and take Hayata’s serves with her forehand. Ito took 61% (16 out of 26) of Hayata’s long serves with her forehand and won 56% of those point. In comparison, she won six out of the ten long serves she received with her backhand. Hence, with our limited amount of data there is still no evidence that taking the long serve with her forehand or backhand is better.
Did Hayata choke?
We now present a possible explanation for Hayata’s poor performance on her own serve. Did Hayata choke? Meaning, did Hayata play worse than normal because she was nervous? Serves are one of the first things to degrade in quality when a player gets nervous, and she had more than enough reason to be nervous. Although Hayata has played on the big stage before such as in her 2020 All Japan National Championship title run, to the best of our knowledge this is the closest she has ever gotten to winning a major international event.
We know that body-language reading is mostly pseudo-science, but we are going to call upon our resident body language expert anyway to analyze the following clip. This is at the end of game 4 after Ito had narrowed the lead from 10-7 to 10-9 and then called a “covid time-out” where she asked the umpire to wipe the table. Hayata’s face looks frozen in fear and she is completely stiff while Mima Ito is jumping around when the camera pans out (note that Hayata would call time-out and go on to win the game 11-9). This is completely different from when Ito called a covid time-out at 5-3 in the same game (not shown), during which Hayata was also jumping around and keeping herself loose.
Of course, body-language and facial-expression reading is a completely subjective exercise that largely confirms everyone’s own beliefs, and in our recap we already came to the conclusion that Ito was more clutch than Hayata in game 5. It will be interesting to see if we can find a method to quantify clutchness or other soft skills like anticipation. This is largely an open problem across all sports, but we would argue it is particularly important in table tennis, where even a slight change in timing can completely ruin someone’s game.
At the moment, due to the small sample size and the fact that this is a completely new exercise for us, interpreting the limited data appears to be somewhat akin to reading tea leaves, but we hope that the statistics shared in this post provided some additional insight to Mima Ito’s finals victory over Hina Hayata at WTT Contender. Although some people prefer watching many different match-ups, here’s to hoping for another Ito vs Hayata finals in WTT Star Contender so we can do another round of this type of analysis.