80% of your wine comes from 20% of your grapes

Heard this great little anecdote from a friend over coffee today.  He said he read somewhere (maybe in a book called "The 4 hour work week"?) that it's a well known fact of life in wine making that 80% of your output comes from 20% of your grapes.  So the real trick is figuring out where those 20% are sitting in your vineyard, prioritizing their fertilization, and keeping them watered above the rest of the crop.  Every year is different so you never know reliably where the 20% is going to be.

So are people and work just like grapes and wine?  I know that I like grapes, and people whine about work, so that lends some plausibility to the idea.

And whatever happened to the California Raisins?  I want to see the E! Inside Story.