Inside a valuation: Santiago Castro
From the model's €2.2M starting point to €39.7M, one input at a time, and where that lands against an observed €32M.
Built from Published SHAP output for the served Model A (reports/explainability); the player was in its training data.10 chapters
Observed €32MModel A €39.7M (served, in-sample)Serie A · Centre-Forward

Santiago
Castro
Close-up
Image: FootyLogos · image credits
Chapter 01: The valuation
Santiago Castro: 21, centre-forward in Serie A. Transfermarkt's valuation is €32M, in the World Class tier. This story follows how Model A arrives at its own figure, one input at a time.
Chapter 02: Where every estimate starts
Before it looks at this player, Model A sits at €2.2M: its average output across the players it was trained on. Every player's journey starts here. Each input then multiplies the estimate up or down.
Chapter 03: Age
Age (21.7 yrs) raises the estimate ×2.07: from €2.2M to €4.5M.
Across all modelled players this input moves Model A's estimate by ×1.60 on average, in one direction or the other. Here it moves it more than usual.
Chapter 04: Appearances
Appearances (97) raises the estimate ×2.04: from €4.5M to €9.2M.
Across all modelled players this input moves Model A's estimate by ×1.28 on average, in one direction or the other. Here it moves it more than usual.
Chapter 05: League
League (Serie A, Italy) raises the estimate ×1.97: from €9.2M to €18.1M.
Across all modelled players this input moves Model A's estimate by ×1.96 on average, in one direction or the other. Here it moves it more than usual.
Chapter 06: Minutes (last 365 days)
Minutes (last 365 days) (3,443) raises the estimate ×1.33: from €18.1M to €24M.
Across all modelled players this input moves Model A's estimate by ×1.19 on average, in one direction or the other. Here it moves it more than usual.
Chapter 07: European-cup minute share
European-cup minute share (19%) raises the estimate ×1.21: from €24M to €29.1M.
Across all modelled players this input moves Model A's estimate by ×1.20 on average, in one direction or the other. Here it moves it more than usual.
Chapter 08: Everything else
The remaining 15 inputs are individually small. Together they raise the estimate ×1.36, to €39.7M.
Chapter 09: The estimate
After all 20 inputs, Model A says €39.7M. Transfermarkt says €32M. The residual, log(observed) − log(estimate), is −0.216: the observed value is below the estimate, so the model over-predicts by ×1.24.
The served model was trained on this player, so this is an in-sample figure; on unseen players a typical miss is ×1.50.
Chapter 10: What this is not
SHAP describes the model's arithmetic for these inputs. It is not a price, a scouting judgement or a statement about what causes value, and the order of the steps is by size, not sequence.
The same record, with Model B and the player's traits, is in the dossier.
Every Model A valuation starts at €2.2M, the model's average output over the players it was trained on (log 14.592).