Rosternomics
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November 23, 2016

ARISEA

ARI won this trade +$115.2M surplus ARI won this trade +16.2 WAR
ARIARI Dave Stewart net +$115.2M net +16.2
received +$26.4M+$26.4M ± $52M expected surplus · +$247.2M realized received 7.0 ± 6 expected · 34.5 realized WAR
Playoff odds: this deal moved ARI's 2017 odds 77% → 68% (-9 pts) — how trade timing is graded ↗
receives — most valuable first
Ketel Marte2B·24y·B/R
+$15.2M+$15.2M± $42M exp surplusrealized +$243.2M 3.9± 5 exp WARrealized 31.5
Prior
no pedigree — league baseline → 0.21/yr
Evidence
recent form 1.4/yr over 1.0 season
Talent
0.78/yr blended
Horizon
5.0 control yrs
Taijuan WalkerP·25y·B/R
+$11.2M+$11.2M± $31M exp surplusrealized +$4.0M 3.1± 4 exp WARrealized 3.0
Prior
league baseline (track record outweighs draft pedigree) → 0.21/yr
Evidence
recent form 1.1/yr over 1.9 season
Talent
0.77/yr blended
Horizon
4.0 control yrs
SEASEA Jerry Dipoto net −$115.2M net -16.2
received +$74.4M+$74.4M ± $68M expected surplus · +$132.0M realized received 9.7 ± 8 expected · 18.3 realized WAR
Playoff odds: this deal moved SEA's 2017 odds 6% → 10% (+3.3 pts) — how trade timing is graded ↗
receives — most valuable first
Jean Segura2B/SS·27y·R/R
+$76.0M+$76.0M± $18M exp surplusrealized +$64.8M 8.3± 2 exp WARrealized 7.3
Prior
no pedigree — league baseline → 0.21/yr
Evidence
recent form 3.1/yr over 2.3 seasons
Talent
4.15/yr blended
Horizon
2.0 control yrs
Mitch HanigerOF·27y·R/R
+$3.2M+$3.2M± $47M exp surplusrealized +$68.0M 1.4± 6 exp WARrealized 11.1
Prior
#38 overall draft pick → 0.24/yr
Evidence
recent form 0.6/yr over 0.2 season
Talent
0.29/yr blended
Horizon
5.5 control yrs × 0.87 age decline
Zac CurtisP·25y·L/L
−$4.8M−$4.8M± $46M exp surplusrealized −$0.8M 0.0± 6 exp WARrealized -0.1
Prior
#180 overall draft pick — at the league baseline → 0.21/yr
Evidence
recent form -0.4/yr over 1.0 season
Talent
-0.05/yr blended
Horizon
5.5 control yrs

Each player is valued on what he was expected to produce at the time of the trade, versus what he actually produced for his new team.

Expected WAR blends a player's pedigree (Baseball America rank / draft slot, or a baseline) with his recent track record, projected over the years of team control acquired. The ± band is the uncertainty — wide for unproven prospects, tight for established veterans. Surplus values that production at the FA market price of a win (~$8M/WAR) minus salary — so cost-controlled players carry large surplus and expensive ones little, even at the same WAR. Who won is descriptive, not a skill claim: ~99% of a trade's outcome is unforeseeable at the time.

Historically these expected values are unbiased and land within ±2 WAR of reality 75% of the time — yet the side the model favors actually comes out ahead only 53% of the time. The grade is a calibrated bet, not a prediction. Why trades are an efficient market →