MLB issued guidelines to its 30 teams Tuesday that will strongly enhance its rules against the use of illegal foreign substances on baseballs. The updated rules will take effect June 21.

Starting pitchers will be checked by umpires multiple times in an outing. Relievers will be checked at the end of the inning when they entered a game or when they’re removed. Any pitchers found to have or be using foreign substances in violation of the new rules will be ejected and suspended.

It’s a major step for MLB to address a hot topic in the sport. MLB also is seeking avenues to create more action as batting averages plummet and strikeout rates rise.

As for how the new rules will affect the game, Braves manager Brian Snitker said: “I think it remains to be seen.”

One notable inclusion in MLB’s memo: Teams cannot replace a player who is suspended for any on-field violation on the roster. In other words, the player won’t just be punished individually, but he’ll be hurting his team. The team would have to work shorthanded until the suspended player returns.

“They’re obviously serious about what they’re doing,” Snitker said. “And you know, it will affect a club, if they have a player that’s suspended. If you can’t replace them, and you lose them for that long. I mean, it’s a big deal.”

Commissioner Rob Manfred said in a statement: “After an extensive process of repeated warnings without effect, gathering information from current and former players and others across the sport, two months of comprehensive data collection, listening to our fans and thoughtful deliberation, I have determined that new enforcement of foreign substances is needed to level the playing field.

“I understand there’s a 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.”