Impatience has long been a defining characteristic of Diamondbacks prospect Alfredo Marte. When he is at the plate, assistant hitting coach Turner Ward said, there’s little question what he is there to do. “That can get him in trouble sometimes,” said Ward, Marte’s manager last season at Double-A Mobile. “But also that’s his greatest asset.” With injuries popping up in the Diamondbacks’ outfield, Marte’s offensive potential has thrust him into the conversation for a spot on the Diamondbacks’ Opening Day roster. Though he was sent to minor-league camp in the middle of the month, he was summoned back to the big-league clubhouse when center fielder Adam Eaton came down with an elbow injury. Since returning, Marte has swung the bat well, going 4 for 12 with three home runs in five games. He homered for the second time in as many days on Wednesday afternoon. The final outfield spot appears to be down to either Marte or the speedy Tony Campana. The Diamondbacks always envisioned Marte as a potential impact player, only he isn’t quite the same type of player they had expected. Junior Noboa, the Diamondbacks’ vice president of Latin Operations, said he thought Marte was a five-tool player when he signed him as a 16-year-old out of the Dominican Republic in December 2005. But a few years later, Marte suffered a shoulder injury that robbed him of his strong throwing arm, one that Noboa said was as powerful as that of former Dodger outfielder Raul Mondesi. The Diamondbacks say his arm is now passable, though he’s more suited for left field than right. Noboa also thinks the shoulder played a part in his slow offensive development in the minor leagues. During his first three minor-league seasons in the United States, Marte didn’t hit above .260. “I always had a good feeling that he would come back from that injury and that he would be fine,” Noboa said. “He proved with his bat speed and his swing that he can be a good hitter in the future. Now that he’s matured, he’s a better player.”