First base coach Dave Clark was knocked on his back by a thrown ball during batting practice Saturday evening just minutes after Astros manager Bo Porter discussed the relative good health of his ballclub. Clark was on his back for several minutes as players and coaches rushed to him behind the screen in shallow center field as an Astros player sprinted into the visitor’s clubhouse to call on trainer Rex Jones, who sprinted out to check. Standing behind a screen to protect him from batted balls, Clark was hitting fungoes to the outfielders and never saw the infielder Nate Freiman’s errant throw. “Really and truly that’s the last thing on [...]