Being 19 games below .500 four contests before the midway point of a 162-game season doesn’t create an image of a Major League Baseball team that has exceeded expectations. The rebuilding Astros have done just that, though, pitching sharper, occasionally hitting better and winning more tight games than most thought possible when spring training began in February. Since May 15, the Astros are 19-18. A young club with a first-year manager has racked up six- and four-game winning streaks during the span, while winning seven of 11 heading into a two-game series against St. Louis that begins Tuesday at Minute Maid Park. The Astros were initially undone by a 10-30 [...]