Some Yankee prospects don't get overrated. White is a good example of one who gets almost exactly the amount of attention he deserves.
First some background, White's a big guy (6'5") who was drafted by the Yanks out of Baylor all the way back in 2003. He topped out as a prospect when he was rated the #4 Yankee prospect before the 2005 season by Baseball America. Since then his velocity has stuff a little bit and he's had a pair of good, but not great seasons. At this point he's kind of a generic upper minors pitching prospect. He might have some use to a Major League team in the next couple years, but he's not going to become a star.
White will turn 26 next June so the future is now. He needs to fool more of the people more of the time if he's going to get a chance to be in anybody's rotation, let alone a certain team from the Bronx who tends to get really skittish about handing major roles to people who aren't household names. That's alright though because I wonder if White might benefit from a trip to the bullpen. I don't have any in-depth information telling me that it would be a possibility, but he fits the picture of the converted starter. His fastball works mostly in the low 90's, but has reached the mid 90's in his better days. His breaking stuff isn't good enough to get a whole lot of swings and misses. Let him throw one inning at a time and that fastball might sniff 94, 95 mph again and the curve might be more effective just because of the speed differential. One point in his favor as a reliever is that he was lethal against right handed batters in Columbus and not so much against lefties.
The general outlook is what you would assume given the previous couple of paragraphs. As a starter his ceiling is something on the order of a 4th or 5th starter barring him picking up a screwball or cutter or something like that. The downside is the same as every other B-/C+ pitching prospect, he gets hurt and you never hear from him again or he doesn't make any progress and spends the next 7 years learning all about exotic locales like Tacoma, Fresno, Memphis, Buffalo, and Toledo. The midrange is that he becomes a swingman or middle reliever.