Pan Pacific Open: Leylah Fernandez vs Elise Mertens

Research grade

🔬 Research candidateLeylah Fernandez at 92%

Matches a rule that looked positive after costs in the short windows of our Oct 22 2026 backtest. The full-year test without hindsight (Oct 26 2026) found no evidence for any of these rules: out of sample they lost money or were noise. A label for a pattern that once looked good, not an edge and not a recommendation.

• + Quality net +3 or moreNot confirmed. Oct 22 backtest: net +3 when the consensus formed made +7.2 % a trade (n 358), with 5 events giving two thirds of it. Full year, out of sample, the closest rule (3+ proven winners, two thirds on the side) lost −1.9 % a trade (n 49,161, 95 % CI −2.6 to −1.1).
• + ATP/WTA tour match, 70 %+Not confirmed. Oct 22 backtest: +16.6 % (n 164) and +19.0 % (n 120) in two short windows. Full year, out of sample: tennis lost −3.4 % a trade (n 12,026, 95 % CI −4.9 to −1.9); today's top traders, picked with hindsight, made +0.9 % at tour level (n 3,424).
• · Favourite (60–95¢)Full year, out of sample: 0.70–0.90 lost −0.9 % a trade (n 26,050, 95 % CI −1.5 to −0.3): the least bad band, still a loss. The Oct 22 backtest's +0.4 % (n 4,327) was not confirmed.

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.