4572 MLB trades, 1985–2026, each graded on what every player was expected to produce at the time — a Bayesian estimate blending his pedigree with his recent track record, over the years of team control acquired — versus what he actually produced for his new team. The ± band on Exp is the predictive uncertainty — wide for unproven prospects, tight for established veterans. That spread is the reason trade outcomes are nearly unforeseeable: deals price at the expected value, and the band is the variance you can't beat. Shown by default as surplus value (that production priced at the FA market rate of a win, minus salary — so cheap, cost-controlled players carry the most value); toggle to raw WAR up top. Filter, sort, export — and click any trade for its own shareable page showing how each player's expected value was built (pedigree prior, recent form, control horizon). Descriptive, not a skill claim — who won a trade is ~99% unforeseeable at the time. A #N badge on a player = his Baseball America top-100 prospect rank that year (hover for detail).