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…

Stijn van

Gassel

GKNetherlands · Excelsior Rotterdam

№ 301696Emerging €1.1M −0.11

Player dossierEredivisie

Stijn vanGassel

GKGoalkeeperGoalkeeper

Club
Excelsior Rotterdam
League
Eredivisie
Nationality
Netherlands
Age
29
Height
186 cm
Foot
Left
Valued
28 May 2026

Reading the valuation

The market values Gassel at €1M. Model A, which never saw Gassel during training, estimates €1.1M: the market value is 11% below that estimate.

That is a factor of ×1.12. 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 €1.5M, 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.

▼ −0.11A €1.1M▼ −0.40B €1.5M
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
36
Minutes
3,240
Started
36/36
Min / app
90
Cards
0Y 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 Gassel…

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 €1M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €1MModel A €1.1M

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 485 goalkeepers

Stijn van Gassel's percentiles among goalkeepers: Minutes, two years 60th, Starts 62nd, Minutes, last 365 days 74th, European club minutes 32nd60thMinutes62ndStarts74thRecent32ndEurope

Dashed ring: the goalkeeper median (50th percentile)

Minutes, last 365 days

Club minutes in the final year of the window: recent involvement, or the absence of it.

2,820 this player1,560 goalkeeper median74th percentile

0peer deciles · median line · this player ●4,970

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
Feb 2014
Peak
€1M
Dec 2023
Model target
€1M
May 2026
Valuations
33
4 club changes
May 2026€1MExcelsior RotterdamValuation the model is trained to reproduce

May 2026: €1M, Excelsior Rotterdam. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2014-02-10€25kVVV-Venlo/Helmond Sport U19
2014-08-16€25kHelmond Sport
2015-02-21€25kHelmond Sport
2015-07-01€25kHelmond Sport
2016-02-05€25kHelmond Sport
2016-07-01€50kHelmond Sport
2017-02-02€50kHelmond Sport
2017-06-21€100kHelmond Sport
2018-03-01€250kHelmond Sport
2018-06-29€250kHelmond Sport
2019-01-21€250kHelmond Sport
2019-07-03€400kHelmond Sport
2020-04-08€325kHelmond Sport
2020-06-29€350kHelmond Sport
2020-10-24€400kHelmond Sport
2020-12-31€400kHelmond Sport
2021-03-16€450kHelmond Sport
2021-10-12€450kExcelsior Rotterdam
2022-01-12€475kExcelsior Rotterdam
2022-06-23€500kExcelsior Rotterdam
2022-09-14€600kExcelsior Rotterdam
2022-11-11€700kExcelsior Rotterdam
2023-03-17€850kExcelsior Rotterdam
2023-06-23€900kExcelsior Rotterdam
2023-12-15€1MExcelsior Rotterdam
2024-03-18€800kExcelsior Rotterdam
2024-05-31€800kExcelsior Rotterdam
2024-10-14€700kNEC Nijmegen
2024-12-17€600kNEC Nijmegen
2025-05-28€450kNEC Nijmegen
2025-10-02€700kExcelsior Rotterdam
2025-12-02€900kExcelsior Rotterdam
2026-05-28€1MExcelsior Rotterdam

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
−0.112

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 →

Eredivisie425 players · median €1M

Valued above 46% of the 425 Eredivisie players.

€75k€500k€3M€20M€1MSee them in the Explorer →

Goalkeepers, all leagues485 players · median €1M

Valued above 48% of the 485 goalkeepers.

€20k€200k€2M€20M€1MSee them in the Explorer →

Where Gassel 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).