By Daniel Chavkin The San Diego pitcher is in the middle of an All-Star season. The Padres and pitcher Joe Musgrove are closing in on a contract extension of five years and around $100 million, according to Dennis Lin and Ken Rosenthal of The Athletic and Jon Heyman of the New York Post. After first breaking into MLB with the Astros, Musgrove was traded to the Pirates as part of the Gerrit Cole trade in 2018. Pittsburgh then sent to San Diego before the ’21 season in a three-team deal. In a year-and-a-half with the Padres, Musgrove has accumulated a 2.97 ERA in 49 starts with the team, current…