FairValue

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Portrait of Willy Boly

Willy

Boly

CBCote d'Ivoire · Nottingham Forest

№ 142310Emerging €431k −0.36

Image: FootyLogos

Player dossierPremier League

WillyBoly

CBCentre-BackDefender

Club
Nottingham Forest
League
Premier League
Nationality
Cote d'Ivoire
Age
35
Height
195 cm
Foot
Right
Valued
3 Jun 2026

Reading the valuation

The market values Boly at €300k. Model A, which never saw Boly during training, estimates €431k: the market value is 30% below that estimate.

That is a factor of ×1.44. 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 €234k, 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.

▼ −0.36A €431k▲ +0.25B €234k
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
11
Minutes
537
Goals
0
Assists
0
Started
5/11
Min / app
49
Cards
1Y 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 Boly…

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 €300k

Checking API
EmergingEstablishedEliteWorld Class€2M€10M€30M€100k€1M€100MMarket €300kModel A €431k

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

Willy Boly's percentiles among defenders: Goals per 90 18th, Assists per 90 17th, Minutes, two years 2nd, Starts 5th, Minutes, last 365 days 4th, European club minutes 61st18thGoals17thAssists2ndMinutes5thStarts4thRecent61stEurope

Dashed ring: the defender median (50th percentile)

European club minutes

Share of minutes played in UEFA club competitions.

0% this player0% defender median61st 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
€500k
May 2011
Peak
€18M
Mar 2020
Model target
€300k
Jun 2026
Valuations
39
5 club changes
Jun 2026€300kNottingham ForestValuation the model is trained to reproduce

Jun 2026: €300k, Nottingham Forest. Dotted lines mark the €2M, €10M and €30M tier boundaries.

Show as a table
DateMarket valueClub
2011-05-12€500kAJ Auxerre
2011-09-27€900kAJ Auxerre
2011-12-24€2MAJ Auxerre
2012-05-23€2.5MAJ Auxerre
2013-01-04€2MAJ Auxerre
2013-05-29€1.8MAJ Auxerre
2013-09-13€1.5MAJ Auxerre
2014-01-13€1.8MAJ Auxerre
2015-02-17€1.2MSC Braga B
2015-07-01€1MSC Braga
2016-02-24€2.5MSC Braga
2016-07-29€2.8MSC Braga
2016-10-31€4MFC Porto
2017-02-22€3.5MFC Porto
2017-06-26€3.5MFC Porto
2018-02-27€5MWolverhampton Wanderers
2018-08-13€10MWolverhampton Wanderers
2018-12-19€10MWolverhampton Wanderers
2019-06-13€12MWolverhampton Wanderers
2019-09-12€15MWolverhampton Wanderers
2019-12-10€15MWolverhampton Wanderers
2020-03-09€18MWolverhampton Wanderers
2020-04-08€14.5MWolverhampton Wanderers
2020-10-13€16MWolverhampton Wanderers
2021-03-18€14MWolverhampton Wanderers
2021-06-08€14MWolverhampton Wanderers
2021-10-05€10MWolverhampton Wanderers
2021-12-23€8MWolverhampton Wanderers
2022-06-15€6MWolverhampton Wanderers
2022-11-03€4MNottingham Forest
2023-06-20€2.5MNottingham Forest
2023-12-19€2.5MNottingham Forest
2024-05-27€2.5MNottingham Forest
2024-12-16€2MNottingham Forest
2025-05-30€1.5MNottingham Forest
2025-10-17€1.2MNottingham Forest
2025-12-09€800kNottingham Forest
2026-03-09€500kNottingham Forest
2026-06-03€300kNottingham Forest

Audit context group-level, not about this player

Audit group
non-UEFA
Population gap, Model A
+0.093 95% CI +0.063 to +0.124
This player, market vs held-out A
−0.362

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 →

Premier League555 players · median €18M

Valued above 1% of the 555 Premier League players.

€150k€1M€7.5M€50M€300kSee them in the Explorer →

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

Valued above 9% of the 2,065 defenders.

€20k€200k€2M€20M€300kSee them in the Explorer →

Where Boly 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).