"The nock and point have to be in line" That's the phrase that confused me. It's only two points, how can they not be in line? You need at least three points to "line something up". It's hard not to put two things in a row. I understand the crankshaft analogy though. So if I draw a line from the nock to tip, any mass that's on one side of the line has to be balanced by equal mass on the other side and this has to be in 3D? So if I spun the arrow between centers and it didn't fly off and kill me, it should fly straight?