On the day after umpire Joe West confiscated an index card from Phillies reliever Austin Davis, Major League Baseball officials stated that pitchers are allowed to use note cards on the field, as long as doing so does not delay the game.
Phillies manager Gabe Kapler:
I think it's great that our pitchers are able to have their game plans on them. I think it takes a lot of mental focus, takes a lot of bandwidth to get out the best hitters in baseball, and when you can just take a little of that off your mind and put it on a card, I think that's helpful for pitchers and good for baseball.