the ump can't and shouldn't "position a player" ... players can play where ever they chose ... however, and of course, the ump should administer all rules correctly ... thats his/her job and thats what they are paid for ... not coaching
Yes and no, an ump can position a player but this is how. By calling obstruction when it occurs and making sure the coaches understand it will be called all game long until they get their fielder off the base when there isn't a play. I never understood why some umps didn't want to make this call, all I can guess is they are watching the ball and not the players.