FairValue

Checking model

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  • EnvironmentOverviewWhat FairValue measures, what it found, where to go next.
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Portrait of James Justin

James

Justin

RBEngland · Leeds United

№ 413220Elite €18M −0.41

Image: FootyLogos

Player dossierPremier League

JamesJustin

RBRight-BackDefender

Club
Leeds United
League
Premier League
Nationality
England
Age
28
Height
183 cm
Foot
Both
Valued
3 Jun 2026

Reading the valuation

The market values Justin at €12M. Model A, which never saw Justin during training, estimates €18M: the market value is 34% below that estimate.

That is a factor of ×1.50. 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 €8.4M, 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.

▼ −0.41A €18M▲ +0.35B €8.4M
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
72
Minutes
5,372
Goals
7
Assists
3
Started
60/72
Min / app
75
Cards
10Y 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 Justin…

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 €12M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €12MModel A €18M

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

James Justin's percentiles among defenders: Goals per 90 91st, Assists per 90 57th, Minutes, two years 88th, Starts 52nd, Minutes, last 365 days 70th, European club minutes 30th91stGoals57thAssists88thMinutes52ndStarts70thRecent30thEurope

Dashed ring: the defender median (50th percentile)

Goals per 90

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

0.12 this player0.03 defender median91st 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
€4M
Jul 2019
Peak
€25M
Jun 2022
Model target
€12M
Jun 2026
Valuations
19
1 club change
Jun 2026€12MLeeds UnitedValuation the model is trained to reproduce

Jun 2026: €12M, Leeds United. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2019-07-24€4MLeicester City
2019-12-10€4MLeicester City
2020-04-08€3.6MLeicester City
2020-07-30€6MLeicester City
2020-10-13€10MLeicester City
2020-12-17€17MLeicester City
2021-03-18€17MLeicester City
2021-06-08€17MLeicester City
2021-12-23€17MLeicester City
2022-06-15€25MLeicester City
2022-11-03€25MLeicester City
2023-06-20€20MLeicester City
2023-10-27€16MLeicester City
2023-12-21€15MLeicester City
2024-05-24€15MLeicester City
2024-12-16€15MLeicester City
2025-05-30€13MLeicester City
2025-12-09€12MLeeds United
2026-06-03€12MLeeds United

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
−0.408

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 36% of the 555 Premier League players.

€150k€1M€7.5M€50M€12MSee them in the Explorer →

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

Valued above 84% of the 2,065 defenders.

€20k€200k€2M€20M€12MSee them in the Explorer →

Where Justin 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).