The MLB amateur draft is different from other drafts like the NFL and NBA drafts in that players often take several years from being drafted until they reach the major-leagues. Phillies pitcher Aaron Nola is the exception to the rule in that he only took a year to reach the majors; most take at least three to four. In that time, players can completely bottom out and never reach the majors.
The Phillies have had bad luck in the draft in recent years, from 2004 with Greg Golson to 2010 with Jesse Biddle, they have had five draft picks and hit on none of them.