FairValue

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Billy van

Duijl

CBNetherlands · AZ Alkmaar

№ 1008564Emerging €921k +0.49

Player dossierEredivisie

Billy vanDuijl

CBCentre-BackDefender

Club
AZ Alkmaar
League
Eredivisie
Nationality
Netherlands
Age
20
Height
190 cm
Foot
Left
Valued
28 May 2026

Reading the valuation

The market values Duijl at €1.5M. Model A, which never saw Duijl during training, estimates €921k: the market value is 63% above that estimate.

That is a factor of ×1.63. Model A's typical held-out miss is ×1.50 either way, so this gap is larger than its usual error.

Without league and club, Model B estimates €1.1M, closer to the market here, although it is usually further off (typical miss ×2.07).

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

▲ +0.49A €921k▲ +0.34B €1.1M
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
9
Minutes
624
Goals
1
Assists
0
Started
6/9
Min / app
69
Cards
0Y 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 Duijl…

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 €1.5M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €1.5MModel A €921k

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

Billy van Duijl's percentiles among defenders: Goals per 90 95th, Assists per 90 17th, Minutes, two years 3rd, Starts 23rd, Minutes, last 365 days 16th, European club minutes 30th95thGoals17thAssists3rdMinutes23rdStarts16thRecent30thEurope

Dashed ring: the defender median (50th percentile)

Goals per 90

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

0.14 this player0.03 defender median95th 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
€25k
Jun 2022
Peak
€1.5M
May 2026
Model target
€1.5M
May 2026
Valuations
11
3 club changes
May 2026€1.5MAZ AlkmaarValuation the model is trained to reproduce

May 2026: €1.5M, AZ Alkmaar. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2022-06-23€25kFC Volendam U21
2022-09-14€125kFC Volendam
2022-11-11€125kFC Volendam
2023-06-23€125kFC Volendam
2023-12-15€125kFC Volendam
2024-05-31€100kFC Volendam
2024-12-10€150kAZ Alkmaar U21
2025-06-09€200kAZ Alkmaar U21
2025-12-02€400kAZ Alkmaar
2026-03-11€800kAZ Alkmaar
2026-05-28€1.5MAZ Alkmaar

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
+0.488

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 →

Eredivisie425 players · median €1M

Valued above 54% of the 425 Eredivisie players.

€75k€500k€3M€20M€1.5MSee them in the Explorer →

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

Valued above 43% of the 2,065 defenders.

€20k€200k€2M€20M€1.5MSee them in the Explorer →

Where Duijl 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).