FairValue

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  • EnvironmentOverviewWhat FairValue measures, what it found, where to go next.
  • EnvironmentTerminalExplore, compare and track players; market, league and model views.
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  • TerminalPlayer ExplorerSearch, filter and sort the player export.
  • TerminalComparison StudioTwo to four players on one scale.
  • TerminalWatchlistsNamed collections, kept in this browser.
  • TerminalMarket LandscapeHow observed value is distributed, and where the model drifts.

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Portrait of Koni De Winter

Koni De

Winter

CBBelgium · AC Milan

№ 490384Elite €18.9M +0.20

Image: FootyLogos

Player dossierSerie A

Koni DeWinter

CBCentre-BackDefender

Club
AC Milan
League
Serie A
Nationality
Belgium
Age
23
Height
191 cm
Foot
Right
Valued
29 May 2026

Reading the valuation

The market values Winter at €23M. Model A, which never saw Winter during training, estimates €18.9M: the market value is 22% above that estimate.

That is a factor of ×1.22. Model A's typical held-out miss is ×1.50 either way, so this gap is within its usual error.

Without league and club, Model B estimates €4.2M, further from the market. Model B is usually further off (typical miss ×2.07): league and club explain much of how the market prices players.

A gap describes the model's arithmetic for this player's inputs, not what the player is worth.

▲ +0.20A €18.9M▲ +1.70B €4.2M
Pitch length is a log value scale fitted to this player's figures. ● observed · ◇ Model A · dashed ◇ Model B · each arc is a residual, log(observed) − log(estimate).
Apps
55
Minutes
4,270
Goals
4
Assists
1
Started
46/55
Min / app
78
Cards
9Y 0R

Club matches, two years to the valuation date

The Valuation Journey

What moves Model A

Asking the prediction API to explain Model A for Winter…

SHAP describes the model's arithmetic for this player's inputs, not what causes market value. Model B can be explained only by the live service; Model A also has a published explanation for the research players.

Model A vs Model B against the observed €23M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €23MModel A €18.9M

Asking the prediction API…

Held-out estimates come from cross-validation, with this player outside the training data: the honest comparison. Served models were refitted on every player, this one included, so they sit closer to the market. Shaded band: Model A's typical miss (×1.50 either way).

Player traitspercentiles vs 2,065 defenders

Koni De Winter's percentiles among defenders: Goals per 90 81st, Assists per 90 38th, Minutes, two years 74th, Starts 53rd, Minutes, last 365 days 63rd, European club minutes 30th81stGoals38thAssists74thMinutes53rdStarts63rdRecent30thEurope

Dashed ring: the defender median (50th percentile)

Goals per 90

Club goals per 90 minutes played in the two years to the valuation date.

0.08 this player0.03 defender median81st percentile

0.00peer deciles · median line · this player ●0.41

No passing, progression or defensive actions exist in the dataset, so no trait claims to measure them.

Valuation history every Transfermarkt valuation on record

First valuation
€400k
Jun 2021
Peak
€23M
Mar 2026
Model target
€23M
May 2026
Valuations
14
4 club changes
May 2026€23MAC MilanValuation the model is trained to reproduce

May 2026: €23M, AC Milan. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2021-06-30€400kJuventus Primavera
2021-12-20€2MJuventus U23
2022-06-20€2.2MJuventus U23
2022-11-11€4MFC Empoli
2023-06-15€4MFC Empoli
2023-12-20€7MGenoa CFC
2024-03-12€10MGenoa CFC
2024-06-05€12MGenoa CFC
2024-12-18€12MGenoa CFC
2025-03-25€18MGenoa CFC
2025-06-17€22MGenoa CFC
2025-12-23€20MAC Milan
2026-03-24€23MAC Milan
2026-05-29€23MAC Milan

Audit context group-level, not about this player

Audit group
UEFA
Population gap, Model A
+0.093 95% CI +0.063 to +0.124
This player, market vs held-out A
+0.199

The group comes from first-listed citizenship and is never a model input. Across the population, non-UEFA players' market values sit about 10% above Model A's held-out estimates, relative to UEFA players in the same leagues. One player's residual says nothing about that pattern (typical miss ×1.50), and none of it is evidence of discrimination: the target may itself be biased. Open the Fairness Audit

In context observed value among comparable players in this build

All players in the Terminal →

Serie A507 players · median €5.5M

Valued above 87% of the 507 Serie A players.

€100k€750k€5M€30M€23MSee them in the Explorer →

Defenders, all leagues2,065 players · median €2M

Valued above 93% of the 2,065 defenders.

€20k€200k€2M€20M€23MSee them in the Explorer →

Where Winter appears

Watchlists and the comparison tray are kept in this browser only.

Near this valuation closest observed values: same league, then same position

Counts and ranks of observed Transfermarkt values only; model errors are never ranked here. Full player export: Every player in the modelling population (D-011).