By close, the market has absorbed injuries, weather, lineups, and the weight of sharp money, which makes the closing price hard to beat and worth grading against. “The close” needs a convention to be comparable - which book, which snapshot, vigged or devigged - and sloppy conventions quietly corrupt CLV records. On picking a defensible convention: closing-line snapshot conventions.
ParlayAPI archives 1.7M+ historical game closing lines with continuous depth back to 2005 (as of 2026-08) and 30M+ player-prop closing lines since June 2022, served from /v1/historical/sports/{sport_key}/odds - the raw material for CLV grading and closing-line backtests.