MLB.com's No. 15 prospect knows that, to challenge himself, he has to continually work on his biggest weaknesses. If that means his changeup gets hit hard every now and then, he's fine with that.

The D-backs' right-handed prospect scattered four hits over six shutout innings Monday in the Class A South Bend's Silver Hawks' 6-3 win over the Bowling Green Hot Rods.

Bradley (11-5) struck out nine batters, issued two walks and plunked a pair of hitters, but he kept the hosts off the board and received more than enough run support to win his fourth consecutive decision.

"I felt good in the bullpen and that translated into the game," he said. "My fastball command was good, I had a lot of life on my curveball and I even got some popups and ground balls with my changeup.

"The only way to get better is to throw it. I gave up some hits on it, but that will happen. I probably threw it 10 or 11 times which is quite a big step for me. It's a pitch I need to have."

The Oklahoma native is the first Silver Hawks pitcher to win 11 games since Ryan Cook finished 11-11 in 2009. The nine strikeouts are the second-most he has amassed in a game this season, two behind his career high achieved in Lansing on July 29.

Bradley didn't work a 1-2-3 inning, and working out of the stretch, he stranded runners in scoring position in three of his six frames.

He worked around Drew Vettleson's two-out walk in the first inning, and he struck out the side around a free pass to Cameron Seitzer in the second.

Arizona's No. 2 prospect then hit Tyler Goeddel on the wrist with a pitch before stranding pinch-runner Jake Hager at third base in the third, and he skirted around a two-out single to Seitzer in the fourth.

The first two Hot Rods reached base in the fifth against Bradley after Taylor Motter smacked his 13th double of the year and Jake Hager got hit by pitch, but Ryan Brett grounded into a double play and Juniel Querecuto struck out looking.

In the sixth, the Hot Rods put runners on the corners with a pair of two-out hits, but Bradley fanned Joshua Sale on a pitch in the dirt with his 91st and final one of the night.

"It wasn't a start where I was completely dominant," Bradley said. "I walked more guys than I wanted to and I got into jams, but I executed pitches.

"I think this was the fifth time I've started against Bowling Green. They're the best hitting team in the league in my opinion. You can't take one pitch off against any team, especially this team. They have four or five first-rounders and a lot of guys who handle the bat well."

Bradley, who lowered his ERA to 3.62, has not lost in nine starts since surrendering three runs on two hits and five walks over three innings to Lansing on July 1. Over those nine games, he has yielded 16 runs over 47 2/3 innings and recorded 72.

"[The changeup] has been a challenge all year," said the seventh overall selection in the 2011 Draft. "I sometimes bounce it or throw it too high or too hard. But my pitching coach, Wellington Cepeda, emphasizes the importance of having it at High-A and the higher levels.

"I feel like in baseball, the numbers don't tell you everything, especially in the Minor leagues. It's more about being confident and improving every time out. Every time I'm understanding how to pitch and slow the game down."

Bradley's first full season has been largely a transition year for the 20-year-old. Going from high school ball to the professional circuit has been difficult at times, but he is pleased with his progress.

"I think I've done a good job," said Bradley, who signed a contract worth $5 million to be spread out over five years after originally committing to play football and baseball at the University of Oklahoma. "I've walked way too many guys, but I take that with a grain of salt, because I've minimized hits and runs.

"Making 25 or 26 starts, throwing the bullpens, taking the bus trips and playing 150 games -- or however many it is -- is a whole new world from high school baseball. I'll put higher expectations on myself than any media or organization or coach, because I know there is always room to get better."

On Monday, South Bend center fielder Chris Ellison was 3-for-5 out of the leadoff spot, third baseman Ryan Court reached base three times, scored twice and plated a run and left fielder Kerry Jenkins recorded two RBIs.

Bowling Green starter Trevor Shull (5-7) allowed three runs -- two earned -- on three hits and two walks while striking out two batters over 2 1/3 innings before leaving due to an apparent injury. He also uncorked a wild pitch and committed a balk.