I highly admire the guy (hardly a surprise I suspect since I tout the guy's stuff 24/7), and I haven't noticed to that which you allude. It would be helpful if you gave some concrete examples backed up by text as to whatever your thesis is here, which is a bit skeletal in its elucidation. The guy basically is a statistician just like Nate Silver. Both do great work in my opinion.
Well here's some stuff from "The Lost Majority"
"As we've already noted, Clinton carried 99 percent of the counties that had leaned democratic in every election from 1952 through 1988. Obama carried only 39 percent of these counties, even while winning nationally be a similar margin. "
and
"But there is a dirty little secret hiding behind this line of argument. And it is a simple one. The surge in the minority vote we saw in 2008 was the surge in the youth vote. Obviously there is a massive surge among 18 through 29 year olds that far outstrips Obama's improvement maong other age groups. But what happens when nonwhite voters are removed?"