FairValue

Checking model

Esc

  • EnvironmentOverviewWhat FairValue measures, what it found, where to go next.
  • EnvironmentTerminalExplore, compare and track players; market, league and model views.
  • EnvironmentStoriesValuations, head-to-heads and research findings, told as stories.
  • 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.

↑ ↓ to move · Enter to open · Esc to closeLoading player index…

Arnau

Martínez

RBSpain · Girona FC

№ 826224Elite €16.7M −0.51

Player dossierLaLiga

ArnauMartínez

RBRight-BackDefender

Club
Girona FC
League
LaLiga
Nationality
Spain
Age
23
Height
182 cm
Foot
Right
Valued
5 Jun 2026

Reading the valuation

The market values Martínez at €10M. Model A, which never saw Martínez during training, estimates €16.7M: the market value is 40% below that estimate.

That is a factor of ×1.67. 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 €16.9M, 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.

▼ −0.51A €16.7M▼ −0.52B €16.9M
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
75
Minutes
5,901
Goals
5
Assists
6
Started
69/75
Min / app
79
Cards
12Y 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 Martínez…

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 €10M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €10MModel A €16.7M

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

Arnau Martínez's percentiles among defenders: Goals per 90 78th, Assists per 90 75th, Minutes, two years 92nd, Starts 76th, Minutes, last 365 days 83rd, European club minutes 69th78thGoals75thAssists92ndMinutes76thStarts83rdRecent69thEurope

Dashed ring: the defender median (50th percentile)

Minutes, two years

Total club minutes in the two-year window: how much the player was used.

5,901 this player2,860 defender median92nd percentile

451peer deciles · median line · this player ●9,111

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
€300k
Apr 2021
Peak
€15M
Mar 2023
Model target
€10M
Jun 2026
Valuations
16
0 club changes
Jun 2026€10MGirona FCValuation the model is trained to reproduce

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

Show as a table
DateMarket valueClub
2021-04-19€300kGirona FC
2021-06-24€1MGirona FC
2021-12-27€1.5MGirona FC
2022-03-21€3MGirona FC
2022-06-29€5MGirona FC
2022-09-23€6MGirona FC
2022-11-07€9MGirona FC
2023-03-23€15MGirona FC
2023-06-13€15MGirona FC
2023-12-22€15MGirona FC
2024-03-21€10MGirona FC
2024-06-07€10MGirona FC
2024-12-27€10MGirona FC
2025-06-09€10MGirona FC
2025-12-12€10MGirona FC
2026-06-05€10MGirona FC

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
−0.514

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 →

LaLiga509 players · median €4M

Valued above 73% of the 509 LaLiga players.

€100k€1M€10M€100M€10MSee them in the Explorer →

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

Valued above 81% of the 2,065 defenders.

€20k€200k€2M€20M€10MSee them in the Explorer →

Where Martínez 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).