The Chicago Cubs and shortstop Starlin Castro are working on a long-term extension that would be six or more years in length, according to David Kaplan of CSN Chicago. The deal is expected to be finalized before the end of the 2012 season and would buy out two of Castro's free agent years.

The deal is a no-brainer for the Cubs, and a long-term deal always make sense for a young player like Castro. The Cubs can lock up a budding star while Castro minimizes the risk of getting hurt when he hits the open market.

"If Castro continues to develop into one of the best shortstops in baseball and he reaches free agency in four years, he will be unbelievably expensive to retain for the Cubs," the source told me. "This is very smart business by Theo Epstein and Jed Hoyer. They will know what their costs are for a significant amount of time going forward and for Castro, he will have lifetime security rather than going year-to-year during arbitration until he completes six full years in the game.

The 22-year-old Castro isn't having quite the year expected of him after his impressive campaigns in 2010 and 2011. He is batting .276/.307/.422 in 495 plate appearances over 116 games.