ESPN: Olney: Pine tar in the postseason could put MLB in a sticky situation

Because everybody in the room will understand that most pitchers participating in the postseason probably use sunscreen or pine tar or something that violates baseball’s rule against the use of foreign substances. [...]

But everybody involved in the sport knows how prevalent the use of sunscreen and pine tar and other stuff has become. Many catchers have pine tar on some part of their person, to apply as needed. Baseball officials would prefer that no foreign substances are used, but they also understand the practical reality: that the baseballs provided for the players are slick, and not always properly prepared.