MLB.com's Jim Callis has the Pirates taking Mike Nikorak, a righty from Stroudsburg High School in Eastern Pennsylvania. MLB ranks Nikorak the sixth-best prospect in the draft (although most other services don't rank him quite so highly), noting that he throws in the mid-90s and could eventually have a good curve and a reasonable changeup. He's 6-foot-5 and projectible, so ... you know. He's committed to the University of Alabama.
Callis has the Pirates passing on Georgia high school shortstop Cornelius Randolph and Cincinnati outfielder Ian Happ, who have been connected to the Bucs in other recent mocks. (Happ heads to the Cardinals at No. 23, which seems about right.) Nikorak, by most accounts, has legitimate upside, but high-school pitchers are always risky. Neal Huntington is about to head into his eighth draft, and the Pirates haven't yet gotten a high school pitcher to the majors, even though they've drafted about a million of them. They do, of course, have several high school pitching draftees in the minors who have potential, but the fact that the best of them, Tyler Glasnow, was a relatively unheralded fifth-round pick perhaps ought to tell us something.