Alpha scoring as residual return, not zero-vs-PnL

The market-neutral / alpha league should not compare participants to cash or to zero. That would be too weak and too easy to game.

Instead, the score should be based on return after stripping out realized market and sector exposures. In other words, participants are judged on residual return and the stability of that residual return.

This makes the league much more credible as a scouting tool for systematic or quasi-systematic PMs.