"It's because of who he is and the success he's had," Mattingly said of Broxton, who saved last year's All-Star Game but also lost his job in August to Hong-Chih Kuo, whose brittle elbow prevents him from assuming the job full time.
"Sometimes things start snowballing and it's hard to get out of that. All we can do is learn from our mistakes and move forward. If I'm him, I don't want to keep talking about the past. I think he's in a good frame of mind."
Although Broxton's fastball lost several miles an hour last year, management is convinced his problem isn't the arm but his confidence. Mattingly began working on that when last year ended, and if he has a Plan B should Broxton wobble again, he's not saying.
"I don't want to get into hypotheticals," he said. "I'm counting on him pitching good, and I told him that. I'm not concerned with anything that happened last year. I'm counting on Jonathan being the closer and pitching well and being what he's been his whole career."
Broxton said he didn't wallow in his second-half failures last year, in part because of Mattingly's vote of confidence.
"I felt great when he told me, but I still got to go out and pitch and do my job," he said.
He said he didn't spend time over the winter reflecting on the 2010 season, but he changed his offseason training by doing more running.
"Last year was last year," he said. "Just knowing myself, I'll be fine this year. I just had a bad second half. I felt fine, it just wasn't working out in my favor. Radar guns are different in every stadium. Velocity is not my concern. I felt like I needed to do more running to get my legs under me a little bit more."
Otherwise, he said he hasn't made any major changes.
"Just stay with everything you have," he said. "No sense changing what you're doing. I had a great first half. I hit a little bump in the road where nothing was working out for me, but there's no sense changing mechanics. I've played all my life. I know how to throw."
He said he's not concerned that some in the organization have floated the idea that Vicente Padilla could slide into the role of closer should Broxton fail.
"As long as we're winning, it'll be fine," Broxton said.
Broxton had a 2.11 ERA before the All-Star break, but 7.13 after it, presumably triggered by a June 27 48-pitch, ninth-inning meltdown against the Yankees. Prior to last season he signed a two-year contract that pays him $7 million this year, after which he will be eligible for free agency.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.