Swimming Question of the Week - January 19, 2011

This week's question comes from a Masters swimmer who recently read about the 6-world-record swim by Laura Val.  

Here's a link to an article about Laura Val.

Here's the question:
There are now a few swimmers like Laura Val (also Michael Phelps and Karlyn Pipes-Neilsen) who are elite at the other strokes, but who aren't quite at the same elite level in breaststroke.  (We're not taking anything away from their breaststrokes; it's just that they are a little stronger in the other 3 strokes.)   These versatile "non breaststrokers" now often win the IMs, when in the past it seemed that breaststrokers dominated the IMs.    Why might this be happening?