DENVER – The Astros had one of the worst bullpens in baseball in 2012. Statistically, it has been even worse this season. Entering Thursday, the Astros’ 4.80 ERA ranked last out of 30 teams, and the relievers’ combined 1.48 walks and hits per innings pitched was tied with Philadelphia for last. The Astros have been an improved team since mid-May, though, going 7-7 in their last 14 games following Thursday’s 7-5 win at Colorado. A settled starting rotation, improved situational hitting and a stronger bullpen have been at the center of the Astros’ step forward. And while the club’s collection of unproven relievers has started to believe it can pitch [...]