A half-dozen scouts stood behind a chain-link fence Wednesday, making a spring training game between the High Class-A affiliates of the Tigers and Astros actually seem important. And in a way it was. Tigers right-hander Rick Porcello, the subject of trade speculation, started the minor-league game because it was his day to pitch and the parent club was off. Yet it quickly became evident — as it has been evident all spring — that if the Tigers move Porcello, they’re nuts. “His confidence level is so high. I’ve never seen him like that,” said Tigers backup and former Royals catcher Brayan Pena, who caught Porcello on Wednesday. “He’s taking it to another level. His competitive nature is coming out.” Porcello’s seven scoreless innings against Class-A competition meant little. His 2.50 ERA, 18 strikeouts and zero walks in 18 major-league innings this spring mean little more. What matters is Porcello’s aggressive, self-assured demeanor. What matters is the carry on his four-seam fastball, the snap in his curveball, the indications — one after another — that he is on the verge of a career breakthrough.