Ventura's fastball hit 98-99 mph, and he pinpointed his changeup and curve. Ventura gave up one run on six hits, walked just one and struck out six.
Ventura has now given up just three runs over 19 innings in his last three starts -- his best three-start stretch of the season.
"Looks to me like he's starting to get his swagger back," Royals manager Ned Yost said.
"I agree with what Ned said," Ventura said through interpreter Jeremy Guthrie. "I'm able to pitch inside with confidence. That's big for me."
Against the Red Sox, Ventura sailed through the first five innings without allowing a run.
"I felt like I had all my pitches working," he said. "I was able to locate everything pretty well tonight.
"For me, for anyone really, it's a confidence thing. And the last three outings have given me a lot of confidence to be the pitcher I want to be and expect to be and the one who can help this team."
After numerous struggles this season with his command and with controlling his emotions, Ventura can't explain what has been different lately.
"Really nothing except that I'm working hard in between starts and I'm in a good groove now," he said. "I hope it continues."
Jeffrey Flanagan is a reporter for MLB.com. Follow him on Twitter at @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.