Before asking whether sumo improves late in a tournament, check what your chart counts. If you include both the winner and loser of every decided bout, the combined win rate is 50%. Ten bouts produce ten wins and ten losses. That calculation cannot reveal an opening-day or final-day effect.
A useful comparison starts by naming whose results you want to understand. Here we follow Wakamotoharu through the September 2026 tournament in three fixed five-day blocks, using the official profile checked on 9 October 2026.
One wrestler, three windows
| Period | Sequence | Record | Regulation bouts |
|---|---|---|---|
| Days 1–5 | W L W W L | 3–2 | 5 |
| Days 6–10 | W L L W W | 3–2 | 5 |
| Days 11–15 | W W W W L | 4–1 | 5 |
| Total | 15 days | 10–5 | 15 |
The totals match Wakamotoharu’s official September scorecard. In these windows, he won once more in the final five days than in the opening five.
That does not establish that he always finishes strongly. It is one tournament with changing opponents. To examine the impression, choose the same windows before looking at several tournaments, retain all of them, and report if you changed the boundaries after seeing the results.
Why the whole field can hide the question
Fictional example: ten decided bouts generate 20 wrestler-result rows: ten wins and ten losses. The rate is 10 ÷ 20 = 50%. Twenty decided bouts produce 20 ÷ 40 = 50%. This is an arithmetic property of including both sides of every decision.
If you select only makuuchi-ranked wrestlers and omit opponents visiting from juryo, both sides are no longer necessarily included. The selected group’s percentage can differ from 50%, but the difference is not evidence that the whole day’s sumo was better. Store the bout card’s division separately from each wrestler’s banzuke division.
Choose the table that answers your question
| Question | Population | Useful fields |
|---|---|---|
| One wrestler’s trajectory | The same wrestler throughout | Fixed-window results and opponents |
| A rank group’s pattern | A group fixed at the start | Wins, appearances and opponents’ ranks |
| How the bouts differ | Contested bouts each day | Selected finishing techniques and total bouts |
| How withdrawals affect results | All selected wrestlers and completers separately | Counts, exclusions and differences |
A completer-only comparison follows stable names but excludes people who withdrew. It answers a different question; do not choose it only because its result is more striking.
When you add another day
- Save tournament, day, both wrestler IDs and regulation/playoff type.
- Keep ordinary decisions, defaults, unverified entries and unplayed days distinct.
- Add that day’s decision to the running record and reconcile it with the scorecard.
- For an older correction, retain old value, new value, reason and affected totals.
Our final-day results supply a starting point. Choose a wrestler, return to the official fifteen-day row, and ask which opponent sits behind a particular win.
Further reading: comparable day-by-day samples and how participation changes between opening day and the final day.
Editorial update
This worked example and record checklist replace the previous September snapshot promise. They do not claim a completed audit of every wrestler and day. This page focuses on population choice rather than repeating a general win-rate calculation guide.