I speculated in a different thread, but if you have two mediocre arms in the corners, it may be best to just give up on the right fielder having any effect on runners rounding second when the ball is hit out there, and put the slightly better arm in left to deter the extra base on balls hit there. Making the best of a bad lot.
Or, it's just that with a righty on the mound for the Twins, they want the faster corner outfielder in right to try to combat the lefties in the opposing lineup.