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…

Jon

Aramburu

RBVenezuela · Real Sociedad

№ 661145Elite €18.7M −0.22

Player dossierLaLiga

JonAramburu

RBRight-BackDefender

Club
Real Sociedad
League
LaLiga
Nationality
Venezuela
Age
23
Height
176 cm
Foot
Right
Valued
5 Jun 2026

Reading the valuation

The market values Aramburu at €15M. Model A, which never saw Aramburu during training, estimates €18.7M: the market value is 20% below that estimate.

That is a factor of ×1.25. 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 €24.5M, 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.

▼ −0.22A €18.7M▼ −0.49B €24.5M
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
91
Minutes
6,643
Goals
2
Assists
1
Started
74/91
Min / app
73
Cards
22Y 1R

Club matches, two years to the valuation date

The Valuation Journey

What moves Model A

Asking the prediction API to explain Model A for Aramburu…

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 €15M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €15MModel A €18.7M

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

Jon Aramburu's percentiles among defenders: Goals per 90 46th, Assists per 90 34th, Minutes, two years 96th, Starts 47th, Minutes, last 365 days 94th, European club minutes 69th46thGoals34thAssists96thMinutes47thStarts94thRecent69thEurope

Dashed ring: the defender median (50th percentile)

Minutes, two years

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

6,643 this player2,860 defender median96th 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
€50k
Aug 2019
Peak
€15M
Jun 2025
Model target
€15M
Jun 2026
Valuations
17
4 club changes
Jun 2026€15MReal SociedadValuation the model is trained to reproduce

Jun 2026: €15M, Real Sociedad. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2019-08-07€50kDeportivo La Guaira U20
2019-11-13€50kDeportivo La Guaira U20
2020-04-01€75kDeportivo La Guaira
2020-12-20€100kDeportivo La Guaira
2021-06-05€200kDeportivo La Guaira
2021-10-18€250kDeportivo La Guaira
2022-06-06€300kDeportivo La Guaira
2022-12-29€300kReal Unión Club
2023-06-30€300kReal Unión Club
2023-12-20€300kReal Sociedad B
2024-03-21€2MReal Sociedad B
2024-06-17€2.5MReal Sociedad B
2024-07-19€5MReal Sociedad
2024-12-27€12MReal Sociedad
2025-06-09€15MReal Sociedad
2025-12-12€15MReal Sociedad
2026-06-05€15MReal Sociedad

Audit context group-level, not about this player

Audit group
non-UEFA
Population gap, Model A
+0.093 95% CI +0.063 to +0.124
This player, market vs held-out A
−0.222

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 80% of the 509 LaLiga players.

€100k€1M€10M€100M€15MSee them in the Explorer →

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

Valued above 87% of the 2,065 defenders.

€20k€200k€2M€20M€15MSee them in the Explorer →

Where Aramburu 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).