Berg was a 43rd-round draft pick by the Yankees in 2003 and was acquired by the Cubs for OF Matt Lawton in 2005.
In his last 10 relief appearances for Iowa, Berg is 3-0 with a 1.05 ERA, and in those 17.1 innings has given up 10 hits and charted eight strikeouts along with 10 walks.
When he has been on, Berg's sinkerball has been the key to his success. He has a 2.10 ERA, .216 average against and 18 strikeouts in 34.1 innings overall.
"It's a major-league sinker," Iowa Cubs pitching coach Mike Mason said. "Every hitter that knows him knows that his sinker is coming, and they still have trouble getting on top of it. They beat it into the ground. [Groundball outs] are kind of his forte.
"He's added a cutter and he's added a curveball just to keep guys honest. There is no doubt his sinker is a major league quality pitch right now."
Berg agrees that his sinker is his best pitch.
"Because it's a pitch where I can keep it down, then I can get groundball double plays," Berg said. "[Breaking pitches] have gotten a lot better. I've been able to control my cutter for strikes, so that's definitely coming a long way. I'm also working on a curveball. There are signs that its there, so I need to work on it a little more."
Berg spent over a month on the disabled list earlier this season with rotator cuff tendonitis, rehabbing in Arizona away from the team for several weeks. He said he is back to 100 percent and that the injury wasn't too serious.
"It wasn't too bad," Berg said. "It turned out better than I thought it was going to be, which is always a plus … I'm good to go again."
Mason had only good things to say about Berg's progress since coming off the DL.
"His arm is healthy," Mason said. "He's making more of an effort to work on his secondary pitches. He still needs to learn a little bit more on how to get left-handers out, but the cutter is something he's throwing now and it's going to help him tremendously."
In the meantime, Berg is focusing on one thing at a time, and that is getting batters out.
"One of the main things is I've just stayed more focused and concentrated on how to get the hitter out, and to try to get them to do what I want them to do," Berg said. "The other thing is getting ahead in the count. I've been known to walk a lot of guys, so if I can get ahead in the count, that usually helps out a ton."
As a starter last season between Class AA Tennessee and Iowa, Berg had a 5.16 ERA. This season, he's taken on the challenge of switching to the bullpen and has adapted nicely, Mason said.
"I think it was an easy adaptation," Mason said. "He doesn't have to worry about being such a complete pitcher because he's got that sinker he's going to throw 90 percent of the time, and as a starter when they get to see him three or four times, you really have to throw your other pitches. Now he can just be a power-sinker guy that throws a cutter and a curveball, and they'll only have to complement."
Berg sees himself staying the bullpen for now. He enjoys the spontaneity of relieving and the opportunity to throw any day.
Does he think he'll ever move back to a starting role?
"Not right now," Berg said. "And probably not in the next couple of years or so, but maybe down the line when I learn to control my pitches a lot better."
Justin Berg "Sinking" Opponents
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