JUPITER, Fla. — It only took a few hours after Max Scherzer’s first experiment with the pitch clock for the league to send out a memo clarifying rules the Mets right-hander tried to exploit. 

Major League Baseball’s league-wide email, delivered late Friday night, highlighted the fact that a quick pitch is an illegal pitch.

Pitchers may not deliver a pitch “before the batter is reasonably set in the batter’s box,” the rule states. 

In Scherzer’s eventful Grapefruit League debut Friday in Port St. Lucie against the Nationals, he tested the boundaries of the newly introduced pitch clock.

Facing Victor Robles with a runner on first, Scherzer paused at the set for several seconds, prompting Robles to step out of the box — which a hitter can only do once during an at-bat. 

As soon as Robles stepped back in, Scherzer pitched, and the home-plate umpire ruled it a balk. 

“A quick pitch may be assessed when a pitch is delivered with 8 seconds or less remaining on the Pitch Timer, if, in the umpire’s judgment, the batter, although alert to the pitcher, has not had sufficient time to become reasonably set in the batter’s box,” the rule states. 

When Scherzer began to throw the pitch, Robles’ head and eyes were not yet facing the pitcher. 

Batters must be “in the box and alert to the pitcher” by the 8-second mark of the pitch clock (or else face an automatic strike).

The league has instructed umpires to be wary of pitchers trying to time the delivery of the pitch to coincide with that 8-second mark. 

“You’ve got to push the limits on what you can and can’t do with this. I pressed it today,” said Scherzer, who was charged with a balk and would have been penalized with an automatic ball if the bases had been empty. 

Before the Mets beat the Marlins, 15-4, at Roger Dean Stadium on Saturday, manager Buck Showalter talked with Scherzer about the memo, “among other things.”

Showalter said he expects some adjustments to the rules as the players get accustomed to the pitch clock and try to use it to their advantage. 

Justin Verlander had fewer issues with the rule changes on Saturday, though he acknowledged he will have to cut down on his pacing around the mound.

Verlander tried pitching with his traditional routine to see what he would have to adjust, and he found his strolls — before innings or after outs — will have to be curtailed. 

“Today I got on the mound a couple times and looked up and it was like, I only had seven seconds,” Verlander said after he pitched three innings and gave up a run. “If me and Omar [Narvaez] weren’t on the same page, it could have been a problem.” 

Showalter said the league might tell pitchers they have to communicate with the catcher regarding the sign for the next pitch when they are on the rubber, rather than getting the sign while off the rubber and then quickly delivering. 

“We’re working through this,” Scherzer said Friday. “The umpires, the hitters [and the pitchers].”