He’s not a master of body language. Even when things are going well for Matt Schaub, his shoulders can slump. It’s easy to read too much into such things. But when a ninth-year quarterback who’s played in 118 NFL games is preparing for his first playoff game, everything’s up for consideration. Especially because he’s headed a season-ending slump, during which the Texans lost three of their final four, booting multiple chances to secure a first-round bye and the AFC’s No. 1 seed.