I didn't know that either, so I went to the official rulebook as I don't think that is correct. http://mlb.mlb.com/mlb/downloads/y2016/official_baseball_rules.pdf On page 46, it states: He is touched by a fair ball in fair territory before the ball has touched or passed an infielder. The ball is dead and no runner may score, nor runners advance, except runners forced to advance. EXCEPTION: If a runner is touching his base when touched by an Infield Fly, he is not out, although the batter is out; If a runner is touched by an Infield Fly when he is not touching his base, both the runner and batter are out. On page 61 it states: Rule 6.01(a) Penalty for Interference Comment (Rule 7.08(b) Comment): A runner who is adjudged to have hindered a fielder who is attempting to make a play on a batted ball is out whether it was intentional or not. If, however, the runner has contact with a legally occupied base when he hinders the fielder, he shall not be called out unless, in the umpire’s judgment, such hindrance, whether it occurs on fair or foul territory, is intentional. If the umpire declares the hindrance intentional, the following penalty shall apply: With less than two out, the umpire shall declare both the runner and batter out. With two out, the umpire shall declare the batter out. So it appears to be judgment of the umpire. If a runner is stealing 2nd base and slides safely into the base and a ground ball is then hit up the middle and hits him, he could be safe as long as he didn't do something like reach his hand out to touch the ball. Or in the case where a runner is standing on 3rd base and a rocket of a line drive hits the runner while standing on base, I would believe him to be safe as well.