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Overall, there were encouraging signs as his mechanics continue to be refined.
"He was more out of the attack, so that was good," manager Don Mattingly said. "He's another guy we're looking at and seeing if he is hitting spots and all of that kind of stuff. Obviously, the results were a lot better today."
Jackson, who broke in with the Dodgers in 2003, is a veteran who could add value to Miami in several roles. He's been a starter much of his career, but he was used in relief in 2015 with the Cubs and Braves.
Thursday was just his second Grapefruit League outing. On March 7, he tossed two innings, giving up five runs on eight hits against the Nationals in Viera, Fla.
Throughout Spring Training, Jackson has been throwing frequently on the back fields and tweaking his delivery with Jim Benedict, the Marlins' vice president of pitching development, and pitching coach Juan Nieves.
"Any time we pitch back here, we're kind of working on stuff," Mattingly said. "We'll continue with that path. It makes it easier back here where we're able to mess with pitches and do different things. When you're out there, you're only going to get so many pitches. If you get too many in an inning, then you've got to take him out. Things like that, we can control it back here."
In the final two weeks of Spring Training, Jackson will see where he fits. Ideally, he'd prefer to start, but he will accept whatever happens.
"I think I still have something in the tank," he said. "Obviously, you have some young guns on the team who have a lot of energy. But I still feel like I've got something in the tank."
Jackson has been around long enough to know roles change.
"At this point in my career, I'm all about coming out, competing and having fun," he said. "I'd like to be in the rotation. Some things I can't control, some I can. But at the end of the day, my main objective is to get outs and help the team any way I can."