The two most disappointing hitters on a disappointing Mets club have been Starling Marte and Jeff McNeil.

Marte, who turned 34 this year, has looked old.

It is not age that may have hurt the 31-year-old McNeil, but perhaps the age he is now playing in.

Did Major League Baseball’s push for more offense actually hurt the reigning National League batting champion?

McNeil, whose .326 batting average was the best in the league last year, will enter a three-game set at Citi Field with the White Sox on Tuesday hitting .248.

Plenty of McNeil’s peripherals, including how hard he has hit the ball, are similar to 2022, when he was one of the most consistent hitters in baseball and seemed to always find his way on base.

One aspect that is not similar is the way defenses now line up.

No longer can McNeil survey the field, see a jammed right side and aim for the left.

When opposing teams shifted against McNeil last year (which they did 22.1 percent of the time), the second baseman batted .397.

With regulations on the shift, a magician with the bat has seemed to lack some magic.

“I’ve heard some theories about [how] the lack of shift has actually hurt him,” Buck Showalter acknowledged last month.

Does the Mets manager believe the theories?

“If I did feel that way, I wouldn’t broadcast it,” Showalter said. “He doesn’t need to hear somebody saying that. … It’s nothing that three or four hits wouldn’t solve mentally.”

Those three or four hits have been hard to find. McNeil started well, with an .831 OPS in April, but he has regressed every month since.

McNeil, who has among the best contact ability in the game, is hitting just .171 without a home run in July.

The Mets have waited for their prized bat — who has been hitting third in the order the past few games — to get hot in vain.

In the three games since the break, McNeil has gone 1-for-11.

The lack of shift — partly removed to allow lefty hitters to pull the ball more — likely has taken away at least a few hits from a lefty who can use the whole field.

When McNeil hit the ball on the ground last season, at an average exit velocity of 85.1 mph, he hit .335.

When McNeil has hit the ball on the ground this season, with a similar average speed off the bat of 84.4 mph, he has batted .242.

He has found a lot more frustration than holes.

The quality of the contact has been similar, but the direction has been a bit different.

Last year, McNeil pulled just 33.3 percent of his batted balls.

In 2023 — with no shift and with incentive to simply hit the ball hard rather than aim it — McNeil is pulling balls 37.5 percent of the time.

Maybe his downturn has been shift-related, or maybe luck has not been on McNeil’s side.

When McNeil put any kind of ball in play last year, he batted .353, which was up from a lifetime BABIP of .324.

This year, McNeil’s batting average on balls in play has been .276.

Most of his advanced hitting metrics are similar to last season, but not all of them.

McNeil’s pop-out to Freddie Freeman in Sunday’s fourth inning was his 30th pop-up out of the year; he had 28 all of last season.

Entering Monday, McNeil’s 30 pop-up outs were the eighth-most in baseball, as his infield fly-ball rate has spiked from 6.6 percent in 2022 to 15.9 percent in 2023.

Maybe McNeil’s swing has been off.

Maybe the lack of shift has hindered rather than helped.

Maybe he cannot find any luck.

Maybe the answer is a combination of all three.

But if the Mets are serious about pushing for a playoff spot and not selling at the trade deadline — and curing a hitter whom they locked up to a four-year, $50 million extension this offseason — they will need to figure out the answer.