BOSTON — Alex Cora keeps track of the standings, always aware of just how close the Yankees are to his Red Sox. But Cora, the rookie Boston manager, knows that the landscape really only crystallizes in September, when teams at last get a clear sense of themselves.

“In August, there’s a lot of different teams, because of the trades,” Cora said before batting practice at Fenway Park on Thursday. “Some of them are going to take off because they got better, and some of them are not going to play well. It’s different in August.”

Four days at Fenway in August, with the Red Sox and the Yankees holding the best records in baseball, could tell us a lot about the direction of these old rivals. But it is likely just an appetizer until the end of September, when they meet in two of the last four series of the season.

By then, we will know how each team’s newcomers fit. Second baseman Ian Kinsler batted fifth for the Red Sox on Thursday, and Nathan Eovaldi will start against the Yankees on Saturday. Zach Britton, the star reliever the Yankees poached from Baltimore, was rested and ready.