3,909 valid leaves (1–3 tiles) · equity = avg score advantage over random draw. Thanks to Jason Katz-Brown and
John Chew for underlying work that lead to this analysis.
How to read these charts.
Equity measures how much better (or worse) a given rack leave is compared to the average random draw.
Synergy = actual two-tile equity minus the sum of the two individual tile equities.
Positive synergy means the tiles work better together than you'd expect from their solo values;
negative synergy means they drag each other down (e.g. two "trap" tiles that both discourage the same plays).