NEW YORK — Derek Jeter shook his head. The New York Yankees great and Hall of Fame shortstop thought about 9/11, New York City and the passage of time.“It’s hard to believe it’s been 25 years,” Jeter said.On the 25th anniversary of the Sept. 11 terrorist attacks, the New York Yankees and the New York Mets became the focus of the baseball world Friday, with players and coaches of the Yankees past and present joining a sold-out crowd of 47,410 at Yankee Stadium in remembering one of the darkest days in American history.The final score — Yankees 6, Mets 4 — was mostly an afterthought to many.“Certainly understand the weight of today,” Yankees manager Aaron Boone said.The Yankees brought out stars from the 2001 team, including Jeter, Mariano Rivera, Tino Martinez, Jorge Posada, Scott Brosius and Paul O’Neill.In the afternoon, Boone, Aaron Judge and Gerrit Cole placed a wreath next to a 9/11 memorial in Monument Park.“You go back and think about that day,” Judge said. “I was a young kid, and kind of waking up and my parents are telling me what’s going on, the acts of terrorism that happened. I just remember my mom saying that some bad men did some bad things but there’s a lot of heroes out there right now that are standing up and doing the right thing.“So to get a chance to represent everybody that gave the ultimate sacrifice, it means a lot.”American flags were displayed by fans in the sold-out crowd for the Subway Series opener on the 25th anniversary of 9/11. (Elsa / Getty Images)Fans packed the stands, many of them donning red, white and blue. A half-dozen American flags dotted the bleachers in right-center field.All of the 31 American flags that rim the frieze atop Yankee Stadium were at half-mast. Lee Greenwood sang “God Bless the U.S.A.” before the first pitch.The club also painted the interlocking “NY” behind home plate red and blue with white stars — the same pattern used Sept. 25, 2001, the Yankees’ first home game once the MLB season resumed after a weeklong stoppage after the attacks, the largest of which took place 10 miles south at the World Trade Center.