The Cubs are working on a long-term contract extension for two-time All-Star shortstop Starlin Castro. A team source late Thursday confirmed a report and said talks are progressing. Castro, 22, is in his third season with the Cubs. He made a splash in his big-league debut May 7, 2010, in Cincinnati, where he homered and drove in six runs. He finished fifth in rookie of the year voting after hitting .300.