Under the leadership of commissioner Rob Manfred, Major League Baseball is starting to crack down on pitchers who use foreign substances. Pool Photo-USA TODAY Sports

One of Major League Baseball’s unwritten rules appears set to go by the wayside with the league’s enforcement of foreign substance rules.

In the past, it was virtually unheard of for teams or managers to ask umpires to check opposing pitchers for illegal substances. This was largely the result of a sort of unspoken agreement between teams that their own pitchers would not be scrutinized if they did not target players on other teams. That is not expected to apply now that the league is independently stepping up enforcement.

According to ESPN’s Buster Olney, at least three teams are ready to set aside that agreement and request that umpires check opposing pitchers if they suspect foreign substance use. Once that happens, the unwritten rule will effectively be rendered obsolete, and teams will see themselves as having free reign to request checks on opponents.

“We’ve been telling our pitchers that if they have been using, they need to stop,” one MLB talent evaluator told Olney. “We are looking to level the playing field. The whole sport is looking to level the playing field. We have an expectation our guys will honor the rule. If we get an indication that there’s someone pitching for the other team who might be doing something to gain a competitive advantage, yes, we will want our manager to challenge that.”

It certainly appears that approach is already starting to yield results. The entire league has shielded pitchers for decades. Now that teams are no longer willing to do that, expect pitchers to adjust quickly if they want to avoid punishment.

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