I think these findings are very intriguing. But how about putting this
a bit more to the test, and compare '5 ply random' against '5 ply
legal-move-count'?
I think there is a correlation between black territory and available moves for black. This is one way of thinking about the game: playing moves in order to be able to get more intersections to fill than the opponent. And as others have pointed out, random evaluation tree should return a higher evaluation for branches where there are more leaf nodes.That the reason random evaluation is improved by reading is in fact only caused by choosing lines of play leading to bigger move counts.What would you conclude if say ... 1) move count did much better.