Cruz’s numbers here aren’t a shock — he’s been in the high teens and low twenties for awhile — but Trump hasn’t dipped as low as 25 percent in a national poll since November and Rubio hasn’t seen a number as high as 21 percent since … ever. That makes some righty poll-watchers nervous since PPP’s credibility has been attacked in the past. Not only are they liberal, they were the subject of a famous critique of their methodology by Nate Cohn in TNR a few years ago. If you’re looking to throw out this result, which no other...