PITTSBURGH -- On Saturday morning, a few hours after Starling Marte and Erik Gonzalez had a frightening collision in shallow center field, the Pirates called up a pair of prospects.One of them is a 24-year-old outfielder who is a former top pick and was tearing up Triple-A. The switch-hitter has a .367 average in 13 games, with five homers, three stolen bases, and a strong strikeout-to-walk ratio. He has a .312/.373/.472 slash line in over 1,200 minor league plate appearances. He can play all three outfield spots but is primarily a center fielder.