DENVER — Taijuan Walker aced the tough assignment of pitching at Coors Field in his fifth-career start at the National League’s third-oldest ballpark. Walker lowered his season ERA to 2.70 and picked up his second win of the season in the Mets’ 2-0 victory over the Rockies on Sunday. He hurled seven shutout innings and limited Colorado batters to five hits and two walks. Walker also posted season highs in strikeouts (six) and pitches (97) in his sixth and best outing of the year thus far. It was only the second shutout from a Mets pitcher at Coors Field, ever. The Mets (28-15) improved to 11 s…
