While MLB is set to begin enforcing its ban on pitchers using foreign substances, it's not expected that umpires will begin issuing mass ejections.

Ken Rosenthal of The Athletic reported umpires have been informed to "err on the side of caution" as MLB institutes the controversial midseason change. Numerous players have spoken out criticizing the sport for altering the rules midseason, though this change is more of an enforcement of existing rules than an actual change.

Pitchers using sticky substances on their hands had essentially been a free-for-all for more than a half-decade as the sport saw an increasing obsession with velocity and spin rate.

Los Angeles Dodgers pitcher Trevor Bauer, who has often been accused of being among the worst offenders of using substances to help with grip, ripped MLB in a Twitter thread last week:

Tampa Bay Rays pitcher Tyler Glasnow blamed the crackdown for him suffering a partially torn ulnar collateral ligament and a flexor tendon strain, admitting to using foreign aid in the process.

"Do it in the offseason. Give us a chance to adjust to it," Glasnow said. "But I just threw 80 innings; then you tell me I can't use anything in the middle of the year. I have to change everything I've been doing the entire season. I'm telling you I truly believe that's why I got hurt."

Under the policy, pitchers will be suspended for 10 days if they're found to have used a foreign substance. Umpires are to check starting pitchers multiple times per game, inspecting their glove, hat and belt; relief pitchers are checked at least once. Closers will be checked prior to pitching.

Umpires also have the discretion to check a pitcher mid-inning if there is any suspicion of foreign aid.

Pitchers will still be permitted to use a rosin bag, but all other uses of foreign aid are banned.