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 Stephen Welsh

Stephen

Welsh

CBScotland · Motherwell FC

№ 403568Established €887k +0.81

Image: FootyLogos

Player dossierPremiership

StephenWelsh

CBCentre-BackDefender

Club
Motherwell FC
League
Premiership
Nationality
Scotland
Age
26
Height
189 cm
Foot
Right
Valued
20 May 2026

Reading the valuation

The market values Welsh at €2M. Model A, which never saw Welsh during training, estimates €887k: the market value is 126% above that estimate.

That is a factor of ×2.26. 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 €1.1M, 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.

▲ +0.81A €887k▲ +0.57B €1.1M
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
33
Minutes
2,527
Goals
1
Assists
1
Started
30/33
Min / app
77
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 Welsh…

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 €2M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €2MModel A €887k

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 Welsh's percentiles among defenders: Goals per 90 53rd, Assists per 90 48th, Minutes, two years 44th, Starts 72nd, Minutes, last 365 days 63rd, European club minutes 30th53rdGoals48thAssists44thMinutes72ndStarts63rdRecent30thEurope

Dashed ring: the defender median (50th percentile)

Starts

Share of appearances started rather than entered from the bench.

91% this player83% defender median72nd percentile

18%peer deciles · median line · this player ●100%

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
€2M
May 2026
Model target
€2M
May 2026
Valuations
16
4 club changes
May 2026€2MMotherwell FCValuation the model is trained to reproduce

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

Show as a table
DateMarket valueClub
2019-08-31€50kGreenock Morton FC
2020-02-05€150kCeltic FC B
2021-01-18€200kCeltic FC
2021-06-28€1.2MCeltic FC
2021-12-31€1.5MCeltic FC
2022-06-27€1.5MCeltic FC
2022-12-13€1.5MCeltic FC
2023-06-26€1MCeltic FC
2023-12-05€800kCeltic FC
2024-05-30€800kCeltic FC
2024-12-03€800kCeltic FC
2025-06-12€1MKV Mechelen
2025-10-08€800kMotherwell FC
2025-12-10€800kMotherwell FC
2026-03-05€1.5MMotherwell FC
2026-05-20€2MMotherwell 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
+0.814

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 82% of the 311 Premiership players.

€20k€150k€1M€7.5M€2MSee them in the Explorer →

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

Valued above 49% of the 2,065 defenders.

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

Where Welsh 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).