Actually, quite a few of them have. Rosario and Escobar were both in the lineup in August 2015 when we went to Yankee Stadium in a pennant race. Buxton rejoined the team shortly thereafter. Only Polanco in our lineup tonight is a young player who hasn't previously been part of a MLB pennant race. (Grossman hasn't either, and I guess Kepler came off the bench.) Pitching side, obviously Hildenberger and Rogers haven't, but Duffey has (and obviously Ervin too). Of those that didn't pitch tonight, Gibson, Colon, Belisle, Perkins, Gee, and Tonkin all pitched in September pennant races before (obviously not all young guys!).