When the Astros arrived at Fenway Park on Thursday afternoon, they toured baseball’s oldest stadium, marveling at the 101-year-old venue that blends history with modernity better than any facility in pro sports. When the Astros left Boston on Sunday, they had been swept in an uneven and at times uncompetitive four-game series, and staying a minute longer in the city of the Green Monster and David Ortiz already was an afterthought. For four games, the Red Sox (18-7) outhit, outpitched and outplayed the Astros. After Boston’s 6-1 victory before a sellout crowd of 36,527, it was clearer than ever the Astros (7-18) are on the opposite end of the baseball [...]