Say this about catcher Mitch Meluskey: The guy's a quick learner. When he sent Meluskey to the minors last March, Astros general manager Gerry Hunsicker told him that he wouldn't be a major leaguer anytime soon unless he worked on his defense and his handling of pitchers. Meluskey, a switch-hitter who batted .353 for Triple A New Orleans last year, did just that, and now he'll split time behind the plate with Tony Eusebio. "His upside is enormous," says manager Larry Dierker. "He could be one of the best offensive catchers in the league. But if he's going to make it with this team, it's going to be because of his defense."