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…

Stephen

Kingsley

LBScotland · Heart of Midlothian FC

№ 184398Emerging €519k −0.04

Player dossierPremiership

StephenKingsley

LBLeft-BackDefender

Club
Heart of Midlothian FC
League
Premiership
Nationality
Scotland
Age
31
Height
178 cm
Foot
Left
Valued
20 May 2026

Reading the valuation

The market values Kingsley at €500k. Model A, which never saw Kingsley during training, estimates €519k: the market value is 4% below that estimate.

That is a factor of ×1.04. 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 €443k, 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.

▼ −0.04A €519k▲ +0.12B €443k
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
26
Minutes
1,718
Goals
1
Assists
0
Started
20/26
Min / app
66
Cards
2Y 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 Kingsley…

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 €500k

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €500kModel A €519k

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

Stephen Kingsley's percentiles among defenders: Goals per 90 65th, Assists per 90 17th, Minutes, two years 27th, Starts 38th, Minutes, last 365 days 29th, European club minutes 73rd65thGoals17thAssists27thMinutes38thStarts29thRecent73rdEurope

Dashed ring: the defender median (50th percentile)

European club minutes

Share of minutes played in UEFA club competitions.

10% this player0% defender median73rd 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
€25k
Aug 2011
Peak
€2.5M
Jun 2019
Model target
€500k
May 2026
Valuations
31
3 club changes
May 2026€500kHeart of Midlothian FCValuation the model is trained to reproduce

May 2026: €500k, Heart of Midlothian FC. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2011-08-15€25kFalkirk FC
2012-02-02€100kFalkirk FC
2012-07-26€50kFalkirk FC
2012-09-21€125kFalkirk FC
2013-03-09€150kFalkirk FC
2013-10-08€200kFalkirk FC
2014-08-12€500kSwansea City
2015-07-01€500kSwansea City
2016-02-09€500kSwansea City
2016-08-01€500kSwansea City
2017-02-20€500kSwansea City
2017-06-28€750kSwansea City
2017-09-18€2MHull City
2018-02-27€2MHull City
2018-09-24€2MHull City
2019-06-28€2.5MHull City
2020-02-27€1.8MHull City
2020-04-08€1.4MHull City
2021-01-18€1MHeart of Midlothian FC
2021-06-03€800kHeart of Midlothian FC
2021-12-31€800kHeart of Midlothian FC
2022-06-27€1MHeart of Midlothian FC
2022-12-13€1MHeart of Midlothian FC
2023-06-26€1MHeart of Midlothian FC
2023-12-05€1MHeart of Midlothian FC
2024-05-30€1MHeart of Midlothian FC
2024-12-03€800kHeart of Midlothian FC
2025-03-12€700kHeart of Midlothian FC
2025-06-17€700kHeart of Midlothian FC
2025-12-10€600kHeart of Midlothian FC
2026-05-20€500kHeart of Midlothian 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
−0.037

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 →

Premiership311 players · median €400k

Valued above 55% of the 311 Premiership players.

€20k€150k€1M€7.5M€500kSee them in the Explorer →

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

Valued above 19% of the 2,065 defenders.

€20k€200k€2M€20M€500kSee them in the Explorer →

Where Kingsley 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).