FairValue

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Portrait of Jakub Kiwior

Jakub

Kiwior

CBPoland · FC Porto

№ 425918World Class €12.9M +1.00

Image: FootyLogos

Player dossierLiga Portugal

JakubKiwior

CBCentre-BackDefender

Club
FC Porto
League
Liga Portugal
Nationality
Poland
Age
26
Height
189 cm
Foot
Left
Valued
28 May 2026

Reading the valuation

The market values Kiwior at €35M. Model A, which never saw Kiwior during training, estimates €12.9M: the market value is 172% above that estimate.

That is a factor of ×2.72. 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 €9.8M, 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.

▲ +1.00A €12.9M▲ +1.27B €9.8M
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
61
Minutes
4,722
Goals
1
Assists
2
Started
50/61
Min / app
77
Cards
6Y 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 Kiwior…

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 €35M

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €35MModel A €12.9M

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

Jakub Kiwior's percentiles among defenders: Goals per 90 39th, Assists per 90 49th, Minutes, two years 79th, Starts 49th, Minutes, last 365 days 85th, European club minutes 95th39thGoals49thAssists79thMinutes49thStarts85thRecent95thEurope

Dashed ring: the defender median (50th percentile)

European club minutes

Share of minutes played in UEFA club competitions.

29% this player0% defender median95th 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
€200k
Jun 2019
Peak
€35M
May 2026
Model target
€35M
May 2026
Valuations
22
4 club changes
May 2026€35MFC PortoValuation the model is trained to reproduce

May 2026: €35M, FC Porto. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2019-06-25€200kZeleziarne Podbrezova
2019-12-15€300kMSK Zilina
2020-07-10€300kMSK Zilina
2020-12-28€350kMSK Zilina
2021-06-26€400kMSK Zilina
2021-10-14€1MSpezia Calcio
2021-12-28€1MSpezia Calcio
2022-03-15€1.8MSpezia Calcio
2022-06-07€3MSpezia Calcio
2022-09-27€6MSpezia Calcio
2022-11-11€6MSpezia Calcio
2022-12-23€8MSpezia Calcio
2023-03-16€20MArsenal FC
2023-06-20€25MArsenal FC
2023-12-19€25MArsenal FC
2024-05-27€30MArsenal FC
2024-12-16€28MArsenal FC
2025-03-18€22MArsenal FC
2025-05-30€28MArsenal FC
2025-09-30€25MFC Porto
2025-12-18€27MFC Porto
2026-05-28€35MFC Porto

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
+1.001

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 →

Liga Portugal423 players · median €1M

Joint 10th highest observed value among 423 Liga Portugal players.

€20k€200k€2M€20M€35MSee them in the Explorer →

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

Valued above 96% of the 2,065 defenders.

€20k€200k€2M€20M€35MSee them in the Explorer →

Where Kiwior 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).