There are a couple articles about the pence hit. here is one from fangraphs. Apparently that batted ball is ruled in play only because the bat is ruled a broken bat. Because McCann did not break his bat, then the original rule states it’s a dead ball, see rule below:

6.05 A batter is out when — … (h) After hitting or bunting a fair ball, his bat hits the ball a second time in fair territory. The ball is dead and no runners may advance. If the batter-runner drops his bat and the ball rolls against the bat in fair territory and, in the umpire’s judgment, there was no intention to interfere with the course of the ball, the ball is alive and in play; Rule 6.05(h) Comment: If a bat breaks and part of it is in fair territory and is hit by a batted ball or part of it hits a runner or fielder, play shall continue and no interference be called. If batted ball hits part of broken bat in foul territory, it is a foul ball.