Celtics vs. Bucks: O/U 220.5

Research grade

⚠️ AvoidUnder at 100%

Matches a pattern that lost clearly more than the plain consensus in our tests.

• − BasketballFull year, out of sample: basketball lost −4.8 % a trade (n 1,747, 95 % CI −9.2 to +0.3); Oct 22 backtest: −12.0 % and −9.2 % in its two windows.
• ≤ Side priced over 95¢Full year, out of sample: 0.90–0.95 −0.2 % a trade (n 12,989, 95 % CI −0.6 to +0.3); above 95¢ little is left to win and the tests stop at 0.95.
• ≤ Spread or totalOct 22 backtest: spreads and totals −14.5 % a trade in spring (95 % CI −27 to −1), +1.5 % in October: no edge.

The rules come from our Oct 22 2026 backtest (one entry per market, held to resolution, after a 1¢ half-spread and Polymarket's taker fees). Our full-year test without hindsight (Oct 26 2026) found none of them profitable out of sample, and the plain consensus lost −3.0 % a trade. The grade describes the market; it is not a forecast, not an edge and not advice.