In three years, prospects Carlos Correa, Jonathan Singleton and George Springer could form the core of the Astros’ lineup. Wednesday, the promising trio were starters. The majority of the Astros’ every-day players were given the day off, allowing Correa to start at shortstop, Singleton at first base and Springer in center field. “It’s all about evolution. It’s all about opportunity,” said manager Bo Porter. Correa was the No. 1 overall pick of the 2012 amateur draft. Singleton is the Astros’ No. 2 overall prospect, according to Baseball America, while Springer is No. 3. Correa’s first at-bat resulted in a smooth single to center field, with the 18-year-old pushing a shot [...]