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R.J. Koster

Team Michi

W–L
0–2
Won and lost rating-eligible matches in the past 12 months.
Gi
1,139
Rating based on Gi matches in the past 12 months.
No-Gi
-
Rating based on No-Gi matches in the past 12 months.
Current form
0–2
Results from the ten most recent rating-eligible matches.
Opponents
1
Unique opponents faced in rating-eligible matches in the past 12 months.

Indexed career

Matches

4
Indexed competition matches
Date Opponent Result Event Division
2026-04-18 Mikael Nadirian
Loss
2026 AGF Netherlands Championships Gi · Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
2026-04-18 Mikael Nadirian
Loss
2026 AGF Netherlands Championships Gi · Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
2025-04-05 Joe Smol
Loss
2025 AGF Amsterdam Championships Gi · Gi Kids / Boys / Pre Teen (10 - 11 yrs) / White / Feather I (Up to 29.50 kg)
2025-04-05 Joe Smol
Loss
2025 AGF Amsterdam Championships Gi · Gi Kids / Boys / Pre Teen (10 - 11 yrs) / White / Feather I (Up to 29.50 kg)

Calculation details

Rating breakdown for the past 12 months

See the published month-end rating and the rating-eligible matches added in each month. Open a month for details.

August 2026 No new matches Change 0 Rating 1,139

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

July 2026 No new matches Change 0 Rating 1,139

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

June 2026 No new matches Change 0 Rating 1,139

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

May 2026 No new matches Change 0 Rating 1,139

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

April 2026 2 new matches · 2 left period Change +17 Rating 1,139

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

2 older matches left the 12-month period: 0 won and 2 lost. The rating is then recalculated across the full network, so the monthly change is not a sum of separate deductions.

New rating matches

This is a current what-if estimate: roughly how much the current rating changes when this match is omitted. These values cannot be added and therefore do not together explain the monthly change.
Loss
April 18, 2026 Mikael Nadirian
2026 AGF Netherlands Championships Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
Method Submission 02:43 2–15
Marginal influence -19
Loss
April 18, 2026 Mikael Nadirian
2026 AGF Netherlands Championships Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
Method Submission 00:25 0–0
Marginal influence -19
March 2026 No new matches Change 0 Rating 1,122

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

February 2026 No new matches Change +10 Rating 1,122

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

January 2026 No new matches Change 0 Rating 1,112

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

December 2025 No new matches Change 0 Rating 1,112

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

November 2025 No new matches Change +11 Rating 1,112

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

October 2025 No new matches Change +7 Rating 1,101

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

September 2025 No new matches Change 0 Rating 1,094

Rating-period composition

Rating matches
2 0
Record
0–2 Previous month 0–2
Opponents
1 0
Events
1 0

No matches were added or left the period. The change comes from the monthly revaluation of opponents across the full network.

Relevant matches
1.2
Official ranking percentile
-
Performance
-

1.2 weighted matches against 1 different opponents across 1 events

Weighted win rate
-
Expected win rate
-
Average opponent rating
1,529
Repeated-opponent share
50.0%
Network connectivity
87.6%

Classification evidence

Why U14?

Within the published period from 2025-09-01 through 2026-08-31, only competition ages recorded at events in the calculation year determine this outcome, with at most one vote per event. Without such an age, the most recent unambiguous earlier competition age is projected to the calculation year; bracket evidence is the final fallback. The newest evidence breaks a tie.

Evidence outcome

  • U14 1 event vote Selected outcome

Registrations and outcomes

2026 AGF Netherlands Championships
U14 · Counts
Competition T-shirt / Youth Small
Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
  • Competition age 12
  • Registered age: u12
  • Source category: u12

Classification evidence

Why ≤ 34 kg?

This outcome uses at most one unambiguous upper weight limit per completed ranking event from 2025-09-01 through 2026-08-31. Only the three most recent eligible events are considered, and the lightest verified upper limit is selected. A higher division is not treated as measured body weight.

Evidence outcome

  • ≤ 34 kg 1 competition event Selected outcome

Registrations and outcomes

2026 AGF Netherlands Championships
Does not count
Competition T-shirt / Youth Small

No matches in the rating period · no valid weight evidence

2026 AGF Netherlands Championships
≤ 34 kg · Counts as a competition event
Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
  • Registered weight class: Feather II (Up to 34.00 kg)
  • Source competition limit: Feather II (Up to 34.00 kg)

2 matches in the rating period

Classification evidence

Why Grey?

This outcome uses the belt category of every rating-eligible match from 2025-09-01 through 2026-08-31. The most-fought category is selected; the newest evidence breaks a tie.

Evidence outcome

  • grey 2 matches in the rating period Selected outcome

Registrations and outcomes

2026 AGF Netherlands Championships
grey · Counts as a match
Gi Kids / Boys / Pre Teen (10 - 11 yrs) / Gray / Feather II (Up to 34.00 kg)
  • Source belt category: grey

2 matches in the rating period