FairValue

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  • EnvironmentOverviewWhat FairValue measures, what it found, where to go next.
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Portrait of Ian Maatsen

Ian

Maatsen

LBNetherlands · Aston Villa

№ 485585World Class €30.6M −0.02

Image: FootyLogos

Player dossierPremier League

IanMaatsen

LBLeft-BackDefender

Club
Aston Villa
League
Premier League
Nationality
Netherlands
Age
24
Height
178 cm
Foot
Left
Valued
3 Jun 2026

Reading the valuation

The market values Maatsen at €30M. Model A, which never saw Maatsen during training, estimates €30.6M: the market value is 2% below that estimate.

That is a factor of ×1.02. 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 €24M, 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.

▼ −0.02A €30.6M▲ +0.22B €24M
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
86
Minutes
4,039
Goals
3
Assists
4
Started
40/86
Min / app
47
Cards
6Y 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 Maatsen…

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 €30M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €30MModel A €30.6M

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

Ian Maatsen's percentiles among defenders: Goals per 90 73rd, Assists per 90 74th, Minutes, two years 70th, Starts 5th, Minutes, last 365 days 71st, European club minutes 88th73rdGoals74thAssists70thMinutes5thStarts71stRecent88thEurope

Dashed ring: the defender median (50th percentile)

European club minutes

Share of minutes played in UEFA club competitions.

23% this player0% defender median88th percentile

0%peer deciles · median line · this player ●85%

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
€1M
Nov 2021
Peak
€40M
May 2024
Model target
€30M
Jun 2026
Valuations
16
5 club changes
Jun 2026€30MAston VillaValuation the model is trained to reproduce

Jun 2026: €30M, Aston Villa. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2021-11-24€1MCoventry City
2022-05-13€5MCoventry City
2022-09-14€7MBurnley FC
2022-10-27€9MBurnley FC
2023-06-01€12MChelsea FC U21
2023-10-09€20MChelsea FC
2023-12-19€20MChelsea FC
2024-03-27€30MBorussia Dortmund
2024-05-29€40MBorussia Dortmund
2024-12-16€32MAston Villa
2025-03-18€28MAston Villa
2025-05-30€28MAston Villa
2025-10-17€25MAston Villa
2025-12-09€25MAston Villa
2026-03-09€30MAston Villa
2026-06-03€30MAston Villa

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
−0.021

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 →

Premier League555 players · median €18M

Valued above 73% of the 555 Premier League players.

€150k€1M€7.5M€50M€30MSee them in the Explorer →

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

Valued above 95% of the 2,065 defenders.

€20k€200k€2M€20M€30MSee them in the Explorer →

Where Maatsen 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).