A good pitch – if not a great one.
Class AA Tennessee pitching coach Dennis Lewallyn, a former instructor in the Arizona Diamondbacks' organization, has compared Berg's power sinker to that of Arizona ace Brandon Webb, and even told Berg that he might have a better one than the Cy Young-winner.
Berg, a 6-foot-4 right-hander, was promoted to Triple-A for the first time in April, and Iowa pitching coach Mike Mason has since had two months to gauge how good the pitch really is.
"To throw a 93, 94, 95-mile per hour sinker that drops two feet, you're talking Brandon Webb," said Mason.
Berg, 24, is still relatively early in his development and has yet to develop control of his talent. But he is seemingly coming to grips with his potential.
"When a pitch moves that much, it's tough to control. But yeah, I didn't really know I had that pitch until [Pratt] brought it up," Berg said. "If I can harness it and throw a lot of strikes with it, I think it's really going to be a plus for me."
Berg was drafted out of Indian Hills Community College (Centerville, Iowa) with the 1,290th overall pick in 2003. He originally committed to play for the University of Iowa, but instead spent the 2004 season in rookie ball with New York.
In 2005, Berg played short-season ball for Class Low A Staten Island, where he first caught the Cubs attention by going 6-2 with a 3.53 ERA in 15 games. Then, on Aug. 26, 2005, New York dealt Berg to the Cubs for former two-time American League All-Star Matt Lawton, who played just 21 games in pinstripes and later tested positive for performance-enhancing drugs.
Iowa catcher Koyie Hill caught Webb's sinker while playing for Arizona from 2004-05, and Hill has a different comparison based on personal experience.
"For me, it's more like Chien-Ming Wang, because he throws his 93, 94 (mph)," Hill offered. "When I was over there with (the Yankees in 2006), I was thinking that Wang's and Webb's are a lot alike, except Wang's is a little bit harder.
"But to me, (Wang's) is more like Berg; he's got that power-sinker. Webb's is heavy and it's located. It's a big one, and Berg's can be big at times. But it's always a lot harder."
Hill added that the comparison to Webb might not yet be a fair tag to apply on Berg.
"The possibilities are definitely there with his movement on his sinker. It's a plus-pitch, it's a big league pitch," Hill said. "He's come a long ways since he's been here, which is a big thing for me. He's learning. He's definitely capable of being a power sinkerball guy at that level. As far as being a starter with that pitch like Webb is, that's an organizational deal."
Berg is the "rawest" starter in Iowa's rotation according to his pitching coach, and Mason said the club is trying to help Berg become more than "just a sinkerballer." He also said the young pitcher will have difficulty developing his four-pitch arsenal because he is still trying to establish a consistent delivery.
"For a guy that really doesn't repeat his delivery because he's not really in rhythm half the time and because the game is just kind of going a little fast for him, you try to slow the game up," Mason said. "But you can't just let him throw nothing but his best pitch. The other pitches, if he's going to be a good pitcher in the big leagues, he's going to have to have something else."
Mason noted that he can usually tell if Berg is going to have good command during pre-game warm-ups and that Berg "is always fun to watch."
A 49-year-old former big league pitcher himself, Mason thinks patience will be a worthwhile investment with regards to Berg.
"He's a kid that has a plus-plus sinker, and that's done most of the damage for him now," said Mason, who is trying to help Berg refine a cutter, curveball and changeup. "Erratic command of a plus-pitch, I mean, that's what the minor leagues are for. If it takes him one, two years two harness that, as long as he doesn't lose that pitch, everybody is going to give him a shot."
Berg has to date allowed 38 earned runs over 13 starts at Triple-A this season. He gave up 19 of those runs in two games alone – a 1 1/3 inning outing on May 5 and a four-inning start on June 17.
But Berg has a 3.05 ERA in his other 56 innings at Iowa and has struck out 36 batters, walked 36 and allowed 60 hits, including 10 home runs.
"Berg has done a great job learning," Hill said. "I enjoy working with him and he is eager to listen and he wants to apply what he's being taught – and when in doubt throw the sinker."
In his last three starts, Berg has given up only four earned runs over 16 innings. He has won three straight decisions.
"I'm starting to feel better now," Berg said. "I feel like my mechanics are coming together a little bit better. I'm trying to get ahead in the count, throw first-pitch strikes, put the ball in play. I realize I'm a contact pitcher … so if I can go ahead and get ahead in the count throwing first-pitch strikes (and) making them put the ball in play earlier, I feel like I can have a more successful outing."
Berg said he is also trying to establish consistent command of his fastball. He has replaced his slider with a cutter.
"It gives me a chance to get the hitter committed earlier, throwing a hard pitch that moves in both directions," he explained. "With my sinker going in to a righty, or my cutter going into a lefty, it gives them something to look at. With the cutter being a hard pitch, it's going to make them commit earlier."
His catcher is already liking the way Berg is using the new pitch.
"Guys keep on leaning out there on the sinker, you know. He's got something to kind of back them off," Hill said of the cutter. "His curveball is coming around; he's still got a little ways to go as far as believing in his changeup, but his other pitches are coming around. That's one of the things that we talk about [that] he's come a long ways with. Before, it was just fastball, sinker, sinker, sinker, and now he's got some other pitches in his arsenal."
Mason thinks that playing on a winning team this season has helped ease Berg's transition to Triple-A. Iowa has the best record of any Cubs minor league affiliate at 58-38, good for a six-game lead in the PCL American Northern Division.
"Justin is one of those kind of guys that takes everything to heart," Mason said. "If he was pitching bad and we were losing, he'd feel terrible and he'd put 10 times more pressure on himself. He knows that with our offense and our experience, we're going to score some runs, so it's OK to give up three, four, five. We can still come back."
As a contact pitcher, Berg agrees that having an experienced team behind him boosts his confidence.
"A lot of these guys have played in the major leagues," he said. "I'm still new to this. I haven't had a lot of experience with guys that can play defense like this. It's great. These guys, they all know their roles and their place, and they'll do everything they can to score you a run. It's an unbelievable feeling when the level of play is like this."