SAN FRANCISCO — The Giants announced this week that they will once again host an exhibition with Team USA next spring ahead of the World Baseball Classic, which is exciting for the organization for reasons other than the fact that the game will bring some of Major League Baseball’s biggest stars to Scottsdale Stadium.When the Giants did the same thing before the last WBC, they hoped to be able to show off their $50-plus million Papago training facility to potential free agent targets. Giants officials were thrilled when they heard that during the workout at Papago, one of the team’s best players FaceTimed his general manager to show off some of the amenities. Perhaps in future years, a player will sign with the organization and note that he wants to spend his winters and springs at Papago. For now, Buster Posey, Zack Minasian and Tony Vitello are tasked with finding contributors who want to be there next spring, and that work starts today. MLB free agency is officially underway, and while most of the heavy lifting is traditionally done around the Winter Meetings in December, Posey showed last year — with Willy Adames —...