One of my very favorite prospects is Brad Miller in the Mariners system. Here is my 2013 Baseball Prospect Book report on him.
Brad Miller, SS, Seattle Mariners
Bats: L Throws: R HT: 6-2 WT: 185 DOB: October 18, 1989
2012: Grade B-
Brad Miller is one of my favorite prospects. A second round pick out of Clemson in 2011, Miller has a fast bat from the left side. He makes contact, controls the strike zone very well, and shows more power potential than most middle infielders. His numbers in the Cal League were not an illusionary result of High Desert, and he continued raking after being promoted to Double-A (wRC+ 151, OPS +24 percent, SEC .326 in the Southern League). If anything, people are still underestimating his bat. Miller also has better-than-average speed and is an effective stealer. His main problem is defense. He has sufficient range and arm strength to handle shortstop, but remains error-prone on routine plays, particularly throws. He showed some improvement with this late in the year, and if I were the Mariners I'd leave him at shortstop as long as possible. Even if he moves to second base, Miller's hitting skills make him a premium property. Grade B+.