Konstantinos
Tzolakis
GKGreece · Olympiacos Piraeus
Image: FootyLogos
Player dossierSuper League
KonstantinosTzolakis
GKGoalkeeperGoalkeeper
- Club
- Olympiacos Piraeus
- League
- Super League
- Nationality
- Greece
- Age
- 23
- Height
- 193 cm
- Foot
- Both
- Valued
- 4 Jun 2026
Reading the valuation
The market values Tzolakis at €18M. Model A, which never saw Tzolakis during training, estimates €12.1M: the market value is 49% above that estimate.
That is a factor of ×1.49. 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 €11.9M, 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
- 72
- Minutes
- 6,479
- Started
- 72/72
- Min / app
- 90
- Cards
- 1Y 1R
Club matches, two years to the valuation date
The Valuation Journey
What moves Model A
Asking the prediction API to explain Model A for Tzolakis…
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 €18M
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 485 goalkeepers
Dashed ring: the goalkeeper median (50th percentile)
European club minutes
Share of minutes played in UEFA club competitions.
26% this player0% goalkeeper median90th 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
- €150k
- Aug 2020
- Peak
- €18M
- Jun 2026
- Model target
- €18M
- Jun 2026
- Valuations
- 18
- 0 club changes
Jun 2026: €18M, Olympiacos Piraeus. Dotted lines mark the €2M, €10M and €30M tier boundaries.
Show as a table
| Date | Market value | Club |
|---|---|---|
| 2020-08-04 | €150k | Olympiacos Piraeus |
| 2020-10-12 | €450k | Olympiacos Piraeus |
| 2021-02-12 | €750k | Olympiacos Piraeus |
| 2021-11-01 | €1.2M | Olympiacos Piraeus |
| 2022-06-27 | €1.2M | Olympiacos Piraeus |
| 2022-11-07 | €1.2M | Olympiacos Piraeus |
| 2023-02-27 | €1.5M | Olympiacos Piraeus |
| 2023-05-22 | €1.5M | Olympiacos Piraeus |
| 2023-12-20 | €1.5M | Olympiacos Piraeus |
| 2024-03-06 | €1.2M | Olympiacos Piraeus |
| 2024-05-30 | €2M | Olympiacos Piraeus |
| 2024-09-26 | €4M | Olympiacos Piraeus |
| 2024-12-18 | €6M | Olympiacos Piraeus |
| 2025-03-14 | €8M | Olympiacos Piraeus |
| 2025-05-23 | €10M | Olympiacos Piraeus |
| 2025-09-23 | €13M | Olympiacos Piraeus |
| 2025-12-12 | €15M | Olympiacos Piraeus |
| 2026-06-04 | €18M | Olympiacos Piraeus |
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
- +0.399
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 →Super League356 players · median €600k
3rd highest observed value among 356 Super League players.
See them in the Explorer →Goalkeepers, all leagues485 players · median €1M
Valued above 94% of the 485 goalkeepers.
See them in the Explorer →Where Tzolakis appears
Watchlists and the comparison tray are kept in this browser only.
Near this valuation closest observed values: same league, then same position
- KonstanteliasAMPAOK Thessaloniki · Super League€22M
- HezzeDMOlympiacos Piraeus · Super League€14M
- MouzakitisCMOlympiacos Piraeus · Super League€25M
- PirolaCBOlympiacos Piraeus · Super League€11M
- VicarioGKTottenham Hotspur · goalkeepers€18M
- UrbigGKBayern Munich · goalkeepers€18M
- HornicekGKSC Braga · goalkeepers€18M
- RestesGKFC Toulouse · goalkeepers€18M
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).