You don't make a risky pick like Paul Ryan if you think the fundamentals favor your candidate. You make a risky pick like Paul Ryan if you think the fundamentals don't favor your candidate. And, right now, the numbers don't look good for Romney: Obama leads in the Real Clear Politics average of polls by more than four percentage points -- his largest lead since April.
The bottom line: veep picks matter, and can swing their home states. But national trends still matter most.
With Paul Ryan on the ticket, Mitt Romney's loss will be conservatism's loss, too. And if Romney wins, then Ryan will a footsoldier in the Romney White House, not an independent power center pushing for conservative policies.