Boris
Lambert
DMBelgium · KV Kortrijk
Player dossierPro League
BorisLambert
DMDefensive MidfieldMidfield
- Club
- KV Kortrijk
- League
- Pro League
- Nationality
- Belgium
- Age
- 25
- Height
- 187 cm
- Foot
- Right
- Valued
- 18 Dec 2025
Reading the valuation
The market values Lambert at €700k. Model A, which never saw Lambert during training, estimates €559k: the market value is 25% above 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 €1.2M, 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.
- Apps
- 38
- Minutes
- 2,507
- Goals
- 2
- Assists
- 0
- Started
- 28/38
- Min / app
- 66
- Cards
- 9Y 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 Lambert…
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 €700k
Checking APIAsking 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 1,687 midfielders
Dashed ring: the midfielder median (50th percentile)
Starts
Share of appearances started rather than entered from the bench.
74% this player69% midfielder median59th percentile
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
- Sept 2019
- Peak
- €1.5M
- Jun 2023
- Model target
- €700k
- Dec 2025
- Valuations
- 17
- 2 club changes
Dec 2025: €700k, KV Kortrijk. Dotted lines mark the €2M, €10M and €30M tier boundaries.
Show as a table
| Date | Market value | Club |
|---|---|---|
| 2019-09-13 | €50k | KAS Eupen |
| 2019-12-13 | €50k | KAS Eupen |
| 2020-10-16 | €50k | KAS Eupen |
| 2021-06-07 | €50k | KAS Eupen |
| 2021-10-06 | €350k | KAS Eupen |
| 2022-01-06 | €500k | KAS Eupen |
| 2022-04-12 | €650k | KAS Eupen |
| 2022-09-07 | €800k | KAS Eupen |
| 2022-11-04 | €800k | KAS Eupen |
| 2023-03-22 | €1.2M | KAS Eupen |
| 2023-06-09 | €1.5M | KAS Eupen |
| 2023-12-19 | €1.5M | KAS Eupen |
| 2024-03-22 | €1.2M | KAS Eupen |
| 2024-06-04 | €900k | KAS Eupen |
| 2024-12-17 | €800k | Willem II Tilburg |
| 2025-05-28 | €750k | Willem II Tilburg |
| 2025-12-18 | €700k | KV Kortrijk |
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
- +0.225
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 →Pro League350 players · median €1.8M
Valued above 19% of the 350 Pro League players.
See them in the Explorer →Midfielders, all leagues1,687 players · median €2M
Valued above 23% of the 1,687 midfielders.
See them in the Explorer →Where Lambert appears
Watchlists and the comparison tray are kept in this browser only.
Near this valuation closest observed values: same league, then same position
- SambuRBFCV Dender EH · Pro League€700k
- TangheCBZulte Waregem · Pro League€700k
- KeybusCMKVC Westerlo · Pro League€700k
- LahssainiCMRAAL La Louvière · Pro League€700k
- RomeuDMSouthampton FC · midfielders€700k
- CoquelinDMFC Nantes · midfielders€700k
- MendyDMWatford FC · midfielders€700k
- PereyraCMAEK Athens · midfielders€700k
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).