Despite a powder blue shirt and a red cap, Nolan Arenado wore a purple heart on his sleeve. “I didn’t know the press conference was going to happen until this morning,” the St. Louis Cardinals third baseman said Tuesday inside the visiting clubhouse at Coors Field, an hour after he’d conspicuously attended the news conference down the hall, watching former Rockies teammate Charlie Blackmon say farewell to a game they both love. “Got a few texts, and I’m happy that all the guys let me know.