DETROIT — Thirty-nine games into a 162-game season, the rebuilding Astros have started extended evaluations at all three of their outfield positions. Left fielder J.D. Martinez, 25, center fielder Robbie Grossman, 23, and right fielder Jimmy Paredes, 24, will be allowed to prove their MLB worth while a struggling club that has lost 11 of 13 continues to try to take slow steps toward becoming competitive at the major league level. Brandon Barnes, 26, and Trevor Crowe, 29, will hold reserve roles, with Barnes serving as the team’s primary backup outfielder. The Astros’ constant roster moves aren’t expected to stop until the 2013 campaign is complete. Outfielders Rick Ankiel and [...]