[Private Dick]

I happen to think that having two dominant ethnic groups which comprise around 80% of a metro's total population does not translate to highly diverse when looking at it from a VERY broad view (as this Rice Kinder study does).

Houston exhibits this, and so do NYC and LA to a somewhat lesser extent.

However, looking at San Francisco metro or San Francisco-San Jose metro, we see that that region has a more equally-distributed ethnic makeup of the 4 largest ethnic groups:

It's roughly 40% White, 20% Asian, 20% Hispanic, and 10% Black