Hart also gets some peace of mind that didn't exist as he went year-to-year.
"In years past, I think I've pressed too much to worry about what would happen next year," he said. "I told them all along I wanted to be here [in Milwaukee], because my family likes it there and it's a comfort level. Not having to worry about that now, I can take a deep breath and go out there and relax."
The extension might not have been fathomable as recently as April, when Hart was coming off an awful Spring Training and was left out of the Brewers' Opening Day lineup and off the All-Star ballot. He was already under the microscope after winning a $4.8 million salary in arbitration, the first player to take the Brewers all the way to a hearing since 1998.
General manager Doug Melvin challenged Hart to prove he was worth it. So Hart went to work.
"I'm anxious to go out there and prove to everybody that I'm worth it," he said in Spring Training. "I told Doug and Gord [Ash, Milwaukee's assistant GM] that I want to go out and prove to them that I'm a guy who could get a long-term deal."
Mission accomplished. Hart made the 2010 All-Star team via the players' ballot and ended up starting for the National League in place of injured Braves rookie Jason Heyward.
Hart carried a .288 average, 23 home runs and 72 RBIs into Monday's game in Chicago. His two-run homer in the sixth inning of Sunday's 5-2 loss in Houston snapped Milwaukee's 28-inning scoreless streak.
He worked with hitting coach Dale Sveum on his swing and eliminated much of the lower-body movement that, according to Hart, had gotten in the way of his plate coverage. He grew comfortable with the contact lenses that had bothered him in the dry Spring Training air of Arizona. And he "got his mental game back," Hart said.
Along the way, Hart started feeling the love again from the fans in the right-field bleachers.
"I think fans saw that the work I was putting in was paying off," Hart said. "They're just like everybody else. They want to see guys go out there and work hard and try to perform better. I think the results come from the hard work I was putting in, and I kind of won them over by going out and performing."
Other teams noticed, too. Hart was the subject of trade rumors throughout June and July, linked to clubs from San Francisco all the way east to Tampa Bay.
"As far as rumors go, as a general manager I have to listen when teams call on any player, in the market we're in," said Melvin. "Who wouldn't want someone that's on pace for 30 homers and 100 RBI? There were teams that called.
"I never judge any trades serious until names are exchanged. It was all about, 'Is Corey available? Is Prince [Fielder] available? Typical trade rumors. ...
"Now, Corey doesn't have to go through this again. Corey has worked hard. We've never had to worry about that. He's always been a good worker."
Once it became clear Hart would not be traded, the deal came together very quickly. Some of the credit for that goes to Hart, who repeatedly made it clear to the reporters asking him about trade rumors that he preferred to stay with Milwaukee, the team that drafted him in 2000. Melvin read those comments and instructed Ash to float the idea of an extension with Hart's agent, Jeff Berry.
About a week later, a few hours before Saturday's non-waiver trade deadline, a deal was in place.
Before these talks, the Brewers had never cruised through previous negotiations with Berry. In 2008, Hart's final pre-arbitration season, the sides were unable to reach a compromise and the Brewers renewed Hart's contract for $444,000. In 2009, after initial talks about an extension didn't progress, the sides didn't strike a deal until the eve of a scheduled arbitration hearing. Earlier this year, the sides went all the way to a hearing.
"I was pushing for [an extension] because it was something I really wanted," Hart said.
With Hart, the Brewers have four players signed past the end of next season. Left-hander Randy Wolf's three-year contract runs through 2012 and includes a club option for '13. Right-hander Yovani Gallardo signed an extension earlier this season that runs through '14 and includes a '15 club option. And left fielder Ryan Braun, a CAA client like Hart, is three years into an eight-year deal that will run through '15.
"Getting a contract done is really a breath of fresh air," he said.