The numbers are from 1984-1999, but a book put out by guys from Baseball Prospectus shows that college hitters drafted are 50% more likely to reach the majors than high schools at equivalent draft positions. The college hitters also provided a higher WAR on average. However, it appears that the WAR advantage of college hitters over high school hitters drafted in the top 100 shrunk as the 90s went on until it was a slight advantage. With this in mind, it would seem to me that Turner is a safer pick than Gordon. I have always preferred Turner over Gordon, but I haven't seen either player play and haven't gone into much depth on their scouting reports.