builtbykev
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Defence was the one conditioning category with no derivable proxy: nothing we ingest measures fielding, and a team's pitchers' hits-allowed conflates pitching with defence and would validate the wrong skill. Statcast publishes Outs Above Average free on the same host as the six feeds already pulled -- verified live at 513 fielders -- so there was nothing to decide. Added as a seventh feed, indexed per fielder and aggregated to team level, which is the unit a batter's prop actually needs: the defence behind the pitcher he faces. Summed OAA is the team's outs converted above average; the mean rides along because a team with more measured fielders would otherwise look better merely for being measured more, and a team with under three measured fielders is absent rather than thin. Unknown is not zero, and it bites unusually hard here: an OAA of 0 is a REAL reading meaning exactly average, so coercing absence to 0 would assert that every unmeasured fielder is league-average -- the most common defensive profile there is, and a fabricated fact rather than a neutral default. team_defense carries as_of_date in its primary key from the first row. statcast_aggregates was built upsert-in-place with a single as_of date, which silently made every backtest leak the games it was predicting and cost a session to find; this makes point-in-time available before it is needed instead of after a wrong answer. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01W1sivYNqY2TS5ftykmHBU9