Adverse selection eating away my Polymarket bot arbitrage profits.

Last post I left a question hanging - the directional bets lost $3,184 when every one was supposed to have at least 7% edge. Analytics scripts I built gave me a clear picture but there is not a single simple answer that explains why my ROI decayed. The main reason was that I was using stale odds (up to 30 minutes fresh) which resulted in adverse selection fills a lot more often than I thought…