The Rangers don't really steal bases, so the determinant for the 1st and 2nd slots is mainly obp, and Mathews and Young are doing well there... Besides, for a rook, 9ths is less pressure. You have to be careful about rooks and their confidence and fanning before the big bats come up could affect his confidence. Hitting 9th in some ways isn't a bad spot, because you'll rarely get pitched around, even on hitter counts, because they don't want to walk you when the top of the order (i.e. the teams best hitters) are coming up.