Buttigieg is making the Democratic race more unpredictable.

Mayor Pete Buttigieg looks out to the audience during a campaign stop in Dover, N.H., July 12, 2019. (Image: Brian Snyder/Reuters)

It’s usually against best practices to telegraph a punch, but Pete Buttigieg knew what he was doing when he previewed his attack against Elizabeth Warren in a digital ad bashing Medicare for All ahead of last week’s debate. The ad predictably…