CLEVELAND — Braden Montgomery has played in only 24 major-league games, but he doesn’t play or sound like a rookie. He extended his on-base streak to 15 games with a walk in the sixth inning of the Sox’ game Sunday against the Guardians. In that stretch, he has slashed .259/.359/.426 with six doubles, one home run, four RBI, nine runs and nine walks. “It’s a daily battle trying to figure out how you’re going to make it happen against a guy each day,” Montgomery told the Sun-Times. “You’re gettin