A new Boston Globe poll puts Barney Frank ahead of his GOP challenger, Sean Bielat, by a 46 to 33 percent margin. That may sound like good news for the incumbent, until you consider that Frank, who was first elected in 1980, has never won a general election by fewer than 20 points -- and that he's notched at least 64 percent of the vote in every race since 1990. It's not hard to see what's going on here. As I wrote back in January, when Scott Brown knocked off Martha Coakley, Massachusetts is a perfect example of how the...