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…

Portrait of Borna Sosa

Borna

Sosa

LBCroatia · Crystal Palace

№ 293194Established €6.6M −0.79

Image: FootyLogos

Player dossierPremier League

BornaSosa

LBLeft-BackDefender

Club
Crystal Palace
League
Premier League
Nationality
Croatia
Age
28
Height
187 cm
Foot
Left
Valued
3 Jun 2026

Reading the valuation

The market values Sosa at €3M. Model A, which never saw Sosa during training, estimates €6.6M: the market value is 55% below that estimate.

That is a factor of ×2.20. 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 €743k, 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.

▼ −0.79A €6.6M▲ +1.40B €743k
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
34
Minutes
1,754
Goals
0
Assists
0
Started
19/34
Min / app
52
Cards
3Y 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 Sosa…

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 €3M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €3MModel A €6.6M

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

Borna Sosa's percentiles among defenders: Goals per 90 18th, Assists per 90 17th, Minutes, two years 28th, Starts 12th, Minutes, last 365 days 12th, European club minutes 72nd18thGoals17thAssists28thMinutes12thStarts12thRecent72ndEurope

Dashed ring: the defender median (50th percentile)

European club minutes

Share of minutes played in UEFA club competitions.

10% this player0% defender median72nd 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
€250k
Mar 2015
Peak
€23M
Jun 2022
Model target
€3M
Jun 2026
Valuations
27
5 club changes
Jun 2026€3MCrystal PalaceValuation the model is trained to reproduce

Jun 2026: €3M, Crystal Palace. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2015-03-17€250kGNK Dinamo Zagreb II
2016-09-14€500kGNK Dinamo Zagreb
2017-03-13€750kGNK Dinamo Zagreb
2017-10-23€1MGNK Dinamo Zagreb
2018-03-18€1.8MGNK Dinamo Zagreb
2018-08-22€6MVfB Stuttgart
2018-12-18€6MVfB Stuttgart
2019-06-05€4MVfB Stuttgart
2019-12-13€3MVfB Stuttgart
2020-04-08€2.7MVfB Stuttgart
2020-07-15€2MVfB Stuttgart
2020-11-26€3MVfB Stuttgart
2021-02-10€6MVfB Stuttgart
2021-03-31€12MVfB Stuttgart
2021-06-09€16MVfB Stuttgart
2021-12-22€20MVfB Stuttgart
2022-06-09€23MVfB Stuttgart
2022-09-21€20MVfB Stuttgart
2022-11-09€20MVfB Stuttgart
2023-03-29€15MVfB Stuttgart
2023-06-22€12MVfB Stuttgart
2023-12-15€8MAjax Amsterdam
2024-05-31€7.5MAjax Amsterdam
2024-12-18€6MTorino FC
2025-06-17€4.5MTorino FC
2025-12-09€4MCrystal Palace
2026-06-03€3MCrystal Palace

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
−0.790

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 12% of the 555 Premier League players.

€150k€1M€7.5M€50M€3MSee them in the Explorer →

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

Valued above 59% of the 2,065 defenders.

€20k€200k€2M€20M€3MSee them in the Explorer →

Where Sosa 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).