Well if you go by DRS he is 4th last. He might be okay this season but there is no denying Reyes will have to move off SS by 2016 at the latest. Its not just groundball he's bad at but things like receiving throws.
http://www.fangraphs.com/leaders.aspx?pos=ss&stats=fld&lg=all&qual=y&type=1&season=2014&month=0&season1=2014&ind=0&team=0&rost=0&age=0&filter=&players=0&sort=10,d