Major League Baseball has asked umpires for more random checks on pitchers for sticky substances, after its crackdown became less effective in the second half of last season.

MLB established regular checks for grip aids last June 21. Hector Santiago of Seattle was expelled on June 27, and Caleb Smith from Arizona was tossed Aug. 18. Both received 10-game suspensions.

“After an initial dip, spin rates due to periodic checks started to rise towards the end of season as players became accustomed to the circumstances for routine umpire check,” Mike Hill, MLB Senior Vice President of Field Operations, wrote in a memo Friday to all team owners, executives, managers, and major and minor league players.

He said, “As such, umpires were instructed to be more cautious and unpredictable in the timings and scope of their checks during 2022 season.”

The Associated Press obtained the memorandum that was first reported by Sports Illustrated.

All starting pitchers were checked by umpires last season. All relievers were also checked. All caps, gloves, and fingertips were checked.

Hill stated that Hill was working with the umpires to make inspections more efficient. “Rather than focusing solely on uniforms and belts the umpires have been provided additional guidance to assist them in determining whether a pitcher’s hands or fingers are contaminated with a foreign substance that is not allowed under the rules.”

Hill wrote that umpires checking pitchers for foreign substances will use their thumbs to inspect for stickiness. He used his thumb to check the pitcher’s thumb and index fingers for sticky substances.

Although the timing of checks may be less random, it seems that the frequency of checks will not change.

Hill stated that starting pitchers should expect more than one mandatory inspection per game. Hill stated that each relief pitcher would be subject to at most one inspection upon entering the game, after the end of the inning in the which he entered, or after he was removed from the game. To avoid delay and allow umpires to inspect the pitcher thoroughly, inspections will take place between innings or after pitches have changed.

Statcast data shows that fastball spin rates dropped from 2,323 revolutions per hour in May to 2,258 revolutions per hour in June. After an owners meeting, plans for the crackdown were first revealed June 3.

The July average was 2,239, but it rose to 2,263 by September.

The season’s major league batting average fell to.244, the lowest level since 1968, the year of the pitcher.

Hill stated that “we now have extensive data, including third-party testing, which shows how foreign substances affect baseball’s performance.” Hill wrote that foreign substances have a significant impact on the speed and movement of the baseball. This gives pitchers an unfair advantage over those hitters our rules prohibit. Another danger of foreign substances is that they can lead to a decline in control. This is because foreign substance use allows pitchers to sacrifice velocity and control for spin.

The velocity was almost unchanged. It increased from 93.6 mph prior to June 3 to 93.7 after.

Each series, pitchers must provide documentation to the team in order to be allowed to use a substance to treat blisters or cut nails. However, treatment can still be done in-game.

Hill wrote that “Catchers or position players could be subject to inspections depending on the circumstances.”

Additionally, an opposing manager can request that the umpire inspect a pitcher or position player if the manager (or any member of his team), observes behavior on field consistent with the use foreign substances.

These checks would be performed between at-bats and not during.

A manager can be disciplined if he makes a request in bad faith. This could include a request to interrupt the pitcher in a critical situation or a routine request that does not have observable evidence. Hill wrote: