I maintain that Burr is an excellent pick. He's Southern but not Haley Barbour Southern; he's from a swing state; conservative but not Jim DeMint crazy; he's won multiple elections; and he's scandal free.
He's not an excellent pick, tho I don't think there is an excellent pick that would be a game-changer for the Mittbot. Burr would be a safe pick, which is why I am surprised he doesn't get more press. Mitt likes to play it safe. He only leaves his comfort zone if he feels the need. Right now he doesn't feel the need to take risks, which is probably one reason The Mitt won't call out The Donald for being an idiot. If the June jobs report is similar to May's, the chances Romney makes a safe boring pick go up.