Major League Baseball reportedly will be taking a hard stance against pitchers using foreign substances on the mound this season.
Per Joel Sherman of the New York Post, Chris Young, MLB's vice president of on-field operations, initiatives and strategy, has informed teams the official rule stating any foreign substance taken to the mound and used on the ball will be strictly enforced.
MLB has had an official rule prohibiting the use of foreign substances on the ball for years, but Sherman noted there has been a "gentlemen's agreement" throughout the sport in which teams don't challenge opponents about things like pine tar or thick sunscreens because "so many pitchers are using something beyond the legal rosin bag."
ESPN's Buster Olney wrote in April 2018 that pitchers' use of pine tar was getting more pronounced and "everybody on the field knows this is happening."
One reason behind the strict enforcement of the rule could be the increased knowledge of how spin rate on pitches and higher revolutions per minute change the way a baseball moves, which can make pitches more difficult to hit.
It's unclear what the potential punishment will be for pitchers who violate the rule. While pitching for the New York Yankees in 2014, Michael Pineda was ejected in the second inning from a start against the Boston Red Sox and received a 10-game suspension for having pine tar on his neck.