Isolated Power
Slugging minus average: extra bases only.
What it actually is. Slugging percentage minus batting average, which strips the singles out and leaves only the extra bases.
What a scout reads off it. Isolated power is the cleanest read on raw power in the traditional stat line, because it does not reward a hitter for a high average the way slugging does. Two hitters slugging .480 with a hundred points of difference in average are not remotely the same player.
Where the lines are. .200 and up is real power, .150 is average, under .100 is a slap hitter.
Batter's Eye: look up anything in baseball