It has been a bad season to be a Rays top prospects. First Hak-Ju Lee  was lost to a season ending ACL tear after a nasty collision while turning a double play (VIDEO HERE ) and now the Rays #1 pitching prospect Taylor Guerrieri  is lost for 12 months or more after undergoing Tommy John surgery today.
Guerrieri was the Rays #1 pick (#24 overall) in the 2011 draft. The draft pick came to the Rays from the Red Sox as compensation for signing Carl Crawford . He opened the 2013 season ranked as the #44 prospect on Baseball America’s Top 100 prospect list and pitched for the Single A Bowling Green Hot Rods where he went 6-2 with a 2.01 ERA with the 51 strike outs and 12 walks in 67 innings of work. His strong performance elevated to the #29th ranked prospect on Baseball America’s mid-season prospect update list.
In a related note,highly recommend that you check this Grantland.com story which includes the ESPN 30 on 30 Short  on Tommy John and Dr. Frank Jobe on the Tommy John procedure.