Baseball is a game of statistics. But one line in the box score shouldn’t be taken too seriously: attendance. As the Globe reported on Friday, the Red Sox have been using some fuzzy math to support the team’s much-ballyhooed Fenway sellout streak, which has ostensibly been chugging along since 2003. The word sellout implies all tickets have been sold. But in fact, for many Sox games, paid attendance falls short of the park’s capacity.