Two key early-season experiments by the Astros haven’t met expectations. Tyler Greene was supposed to fill the hole left at shortstop by Jed Lowrie’s offseason trade to Oakland. Lowrie entered Thursday ranked fifth in the American League in batting average (.373) and seventh in on-base plus slugging percentage (1.092), while Greene didn’t make the Astros’ opening-day roster and was cut during spring training. Brett Wallace was supposed to be the Astros’ every-day first baseman in 2013, and he started at first while batting second in the club’s season opener. But the fourth-year player’s only hit this year came in the first game, and the 26-year-old Wallace was optioned to Class [...]