Major League Baseball announced at a fan event that 13 teams will accept Passbook tickets at their ballparks this season, up from four stadiums last year. It’s confirmed that the Baltimore Orioles, Chicago Cubs, Detroit Tigers, Milwaukee Brewers, Minnesota Twins, Oakland A’s, and Pittsburgh Pirates will start accepting Passbook tickets for the first time in the 2013 MLB season. Additionally, the Kansas City Royals, New York Mets, and San Francisco Giants will accept Passbook again this season, as they did last September. Three more teams will also allow Passbook ticketing, but have yet to make an official announcement. One of those teams may be the Boston Red Sox, a team that allowed Passbook ticketing last year, but was not mentioned in the new report. [via GigaOM]