I have been a big fan of Nate Silver, and I think his reasoning continues to be sound.

I think there are other “bold” picks that Mr. Romney could have made — Senator Marco Rubio of Florida, for instance, or Govs. Chris Christie of New Jersey or Brian Sandoval of Nevada — where the balance of risk and reward would have been a little better. Some of these candidates, especially Mr. Rubio and Mr. Christie, would also have excited the Republican base. But they might also have had a more natural appeal to independent voters, and to demographic groups that Mr. Romney is struggling to win over.Mr. Christie or Mr. Sandoval, also, or Mr. McDonnell of Virginia, would not have carried Mr. Ryan’s burden of being a symbol of a deeply unpopular Congress.But at least Mr. Romney is taking a risk, something his cautious campaign had not been doing much of previously.