The final week of spring training is usually a time for fine-tuning the roster, for deciding on the last bench player or settling on a reliever to round out the bullpen. The Diamondbacks wish they had it so easy. Instead, one week before his club will open the season against the St. Louis Cardinals, manager Kirk Gibson said he doesn’t know who his leadoff man will be. He doesn’t know who will be playing center field or right field. And he doesn’t know if left-hander Wade Miley, who last season was the team’s best starting pitcher, will be in his rotation to open the year. Much of the uncertainty is a result of the loss of Adam Eaton, the high-energy rookie who was expected to man center field and hit at the top of the Diamondbacks order. But Eaton was diagnosed with an elbow strain last week and won’t throw a baseball for a month, and General Manager Kevin Towers said Eaton might not return until June. Then there’s the calf injury that has bothered outfielder Cody Ross for most of the spring. Though Ross said Sunday he was still aiming to be ready by Opening Day, both he and Gibson acknowledged that the most important thing is for him not to suffer a setback, and if that means missing the first few days, or perhaps the first week, of the season, then so be it. With his outfield in disarray, Gibson has decisions to make. The good news, though, is that his deep and versatile roster gives him options. With Eaton certain to start on the disabled list, outfielder A.J. Pollock is the most likely player to replace him on the roster. That would give Gibson three primary outfielders — Jason Kubel, Gerardo Parra and Pollock — and two others in Martin Prado and Willie Bloomquist, who could be options in the outfield, as well. Should Prado see time in the outfield, it would open up third base for Eric Chavez, although Chavez said earlier this spring that he isn’t capable of playing more than three or four days in a row at this point in his career. Bouncing between positions during the season is nothing new for Prado, who did it throughout his career with the Atlanta Braves. “I think that’s been part of my role for a few years,” he said. “I feel when I’m a part of any team, people see me as a guy that we can trust or that we can put up there and he’ll do the job playing any position. I don’t mind at all. We just want to put the best team out there and give our team a better chance to win.”