• Major League Baseball said it will enforce new guidelines around pitchers using foreign substances on baseballs during games.
• The league said new guidelines that empower umpires to search pitchers for foreign substances will take full effect on June 21. 

Major League Baseball said Tuesday it will enforce new guidelines around pitchers using foreign substances on baseballs during games beginning June 21.

The league office announced that it will empower umpires to check pitchers regularly for banned substances, even if clubs don't request searches. Relief pitchers will be searched for foreign substances after the inning they pitched or when they're removed from games.

In addition, MLB said umpires will be urged to check pitchers when they notice "the baseball has an unusually sticky feel to it, or when the umpire observes a pitcher going to his glove, hat, belt, or any other part of his uniform or body to retrieve or apply what may be a foreign substance."

Players caught cheating will be ejected from the contest and suspended with pay for up to 10 games.

MLB investigated complaints from players, collected data, and tested balls used by all 30 clubs in the first two months of the season. It determined "there is a prevalence of foreign substance use by pitchers" throughout MLB and the Minor League level.

The league added third-party research revealed impacted baseballs have better spin rates and movement that provides pitchers with an "unfair competitive advantage over hitters and pitchers who do not use foreign substances, and results in less action on the field."

Pitchers have dominated this season. There have already been six no-hitters thrown, which could break the record of eight no-hitters set in 1884. Pitchers are also holding hitters to league-low batting averages not seen since 1968. After more than 1,900 games this season, MLB hitters have a combined .238 average. 

In a statement, MLB Commissioner Rob Manfred acknowledged "the history of foreign substances being used on the ball, but what we are seeing today is objectively far different, with much tackier substances being used more frequently than ever before."

"It has become clear that the use of foreign substance has generally morphed from trying to get a better grip on the ball into something else — an unfair competitive advantage that is creating a lack of action and an uneven playing field," he added. "This is not about any individual player or club, or placing blame, it is about a collective shift that has changed the game and needs to be addressed. We have a responsibility to our fans and the generational talent competing on the field to eliminate these substances and improve the game."

Game umpires will also examine catchers and positional players if they "observe conduct consistent with the use of a foreign substance by the pitcher." If players refuse umpire checks, they will be ejected from games and suspended.

Teams are responsible for educating players on the rules. Club personnel may be placed on MLB's ineligible list if they're caught encouraging or aiding players using sticky substances.

If players are suspended for the on-field violations, clubs won't be eligible to replace the roster spot, the league said. MLB notified the players union of the new guidelines and could make further changes to penalties in the future. 

"Major League Umpires stand in support of this initiative to eliminate the use of foreign substances in the game," said Bill Miller, president of the Major League Umpires Association, in a statement. "The integrity of the competition is of utmost importance to us. We have worked diligently with MLB to develop an enforcement system that will treat all players and Clubs equally."

Read MLB's complete enforcement plan here.