Or rather... a pure definition of what a balk is. I think it's simply a means to inject some folly into the game.

In the greatest World Series ever played, (1975 Reds vs Red Sox), Luis Tiant was called for balk and afterwards Joe Morgan was asked to comment on it. They played the 'balk' over and over again and there was NOTHING visible.... but Joe insisted there was, he could see it, and I remember him saying something like "it's something he does with his knee".

I think balks are called to snap crowds out of funks, should they happen to fall into one.