The L.A. Angels on Thursday fired veteran visiting clubhouse manager Brian Harkins. As Maria Torres of The Los Angeles Times reports, Harkins is alleged to have supplied visiting players with substances used to doctor baseballs in violation of the rules. Torres goes on to report that Angels officials confirmed the termination of Harkins but provided no further details. 

ESPN's Alden Gonzalez writes that Harkins, who had been with the team for more than 30 years, had been "providing illegal sticky substances in the visiting clubhouse that aided pitchers' abilities to grip the baseball ...". Harkins confirmed to Gonzalez that he had been fired by the team. 

In the official MLB rule book, Rule 3.01 states that, "… No player shall intentionally discolor or damage the ball by rubbing it with soil, rosin, paraffin, licorice, sand-paper, emery-paper or other foreign substance." Rule 6.02 also forbids the pitcher to "apply a foreign substance of any kind to the ball."

Most commonly, pitchers surreptitiously apply pine tar to the baseball in order to improve their grip and at times increase spin rate. Early in the 2018, Trevor Bauer, then of the Indians, touched off some controversy by implying that certain Astros pitchers were using an illegal substance to increase their spin rates. In April of 2014, Michael Pineda of the Yankees was suspended for 10 games for having pine tar on his neck while pitching. 

Although doctoring the baseball has been a part of baseball for almost the entire history of the sport, MLB seems to be getting more serious about enforcing rules against it. Last month, Joel Sherman of the New York Post reported that former MLB pitcher Chris Young, who now works for MLB, "has been touring camps in Arizona and Florida to deliver the message that Rule 6.02 is going to be enforced this year ..." 

For his part, Bauer, now of the Reds, recently told HBO's "Real Sports" that perhaps 70 percent of MLB pitchers use illegal substances to improve their grip on the baseball.