The best group of lefty hitters in New York — in talent and volume — belongs to the Mets. And it is not really close.

The team of Ruth and Gehrig and Mantle and Berra and Reggie and Mattingly and the short right-field porch might have as few as one full-time position player who hits lefty in switch-hitter Aaron Hicks.

Brett Gardner still projects to play at least vs. most righties, but perhaps Clint Frazier cuts into that. Brian Cashman has said a few times this offseason that Luke Voit is the first baseman and Greg Bird is competing for a job. Who knows how and where Jacoby Ellsbury fits, even if healthy.

The big blow is losing Didi Gregorius (Tommy John surgery) for at least two months, perhaps longer. And how have the Yankees replaced their best lefty bat? By enlisting two more righty hitters — Troy Tulowitzki and DJ LeMahieu — of course.

Last season, the Yankees ranked 22nd in the majors in lefty plate appearances, their lowest since 1990. Gene Michael took over as GM near the end of that season and was appalled by how deficient the Yanks had become in capitalizing on their stadium’s dimensions. He worked to restore the historic strength.

For most of his tenure, Cashman had followed his mentor’s philosophy, favoring lefties who got the ball in the air with pull power. But the Yanks have evolved right, in part because advancing shifts hurt lefty pull hitters most of all. Mainly, though, because they gravitated toward the best players available whether in the draft (Aaron Judge), internationally (Gary Sanchez, Miguel Andujar), in trades (Frazier, Voit, Gleyber Torres, Giancarlo Stanton) or in free agency (Tulowitzki, LeMahieu).

“We always care about being diverse, but not at the expense of giving up quality,” Cashman said by phone. “If the better player is right-handed, so be it in our opinion. We feel we are better served in that way than forcing something and dropping down a category in quality just to get balance. That may be wrong, but those are our thoughts.”

The Mets have generated more lefty plate appearances than the Yankees in each of the past two seasons or as often as in the previous 24 seasons combined. That is almost certain to become three straight years — and not only because the Yankees have so few options but because the Mets have quality from that side.

Nothing speaks to the juxtaposition quite like Robinson Cano, one of the best lefty hitters in Yankees history, now being a Met. He and switch-hitter Jed Lowrie join Michael Conforto, Jeff McNeil and Brandon Nimmo to give the 2019 Mets the only roster with five players who were at least 18 percent better than league average in OPS batting lefty against righty pitching (minimum 150 plate appearances).

So what does all of this mean for the New York teams with spring training near?

This is a good time for the Mets to be deep in lefty bats. Patrick Corbin joins the Nationals, but that is in place of southpaw Met killer Gio Gonzalez. And there are only two other lefties currently projected to be in opposing NL East rotations — Atlanta’s Sean Newcomb and Miami’s Wei-Yin Chen, whose teammate Caleb Smith is trying to make it back from a torn lat.

Dominant left-on-left relievers also are limited in the NL East with Atlanta’s A.J. Minter and Jonny Venters, Washington’s Sean Doolittle and perhaps Miami’s Adam Conley.

Still, Brodie Van Wagenen said by phone that “one of our agenda items was to get more balance from the right-hand side of the plate, and adding Wilson Ramos, Keon Broxton, J.D. Davis and Jed Lowrie were key moves to accomplish that.”

Three important issues

1. Can McNeil handle left field well enough to form an all-lefty outfield against righty pitching with Nimmo in center and Conforto in right — or is that too much of a defensive giveaway? Also, McNeil and to some extent Nimmo are going to have to show their 2018 offense was no fluke — for McNeil that included strong work against lefties (which Cano is usually strong at as well).

2. Can Todd Frazier rebound against lefty pitching not only to provide balance but to keep opposing managers from using southpaw relievers for large swaths of the Met order? Frazier hit an MLB-worst .162 vs. lefties last year (minimum 100 plate appearances). But from 2015-17, he hit 36 homers off southpaws, second in the majors to Nelson Cruz’s 41.

3. Do Davis and/or Peter Alonso turn into forces against lefties, especially if Frazier fails? Both have brilliant minor league results against lefties. But will they translate? For example, in 327 minor league plate appearances vs. southpaws, Alonso has hit .336 with a 1.070 OPS.

As recently as 2015 (first) and ’16 (second), the Yanks still ranked among the leaders in lefty plate appearances. The Yanks have ranked 17th and 22nd the past two years. Nevertheless, their .784 OPS vs. righty pitching in 2017-18 was an MLB best, fueled largely by 370 homers, 16 more than any other team.

Three important issues

1. Can Sanchez rebound against righty pitching? Sanchez’s .171 average vs. righties was a major league worst by 13 points. But in 2017, Sanchez hit 25 homers with an .874 OPS against righties. That same season, Judge and Stanton each hit 44 homers against righty pitching — the most by any player, lefty or righty, since Alex Rodriguez hit 47 in 2007.

2. Is Voit for real? Among righties with at least 100 plate appearances vs. righty pitching last year the top four in OPS were Mike Trout, J.D. Martinez, Mookie Betts and Voit at 1.015. If that is the real Voit, then Bird’s counter-active lefty bat is not as vital.

3. When does Gregorius return? Look, the Yanks have a lot of righties who performed well against lefties last year, including rookies Miguel Andujar and Gleyber Torres. But that is not going to stop opponents from feeding righty after righty against them — albeit the main rival Red Sox are likely to have three lefty starters (David Price, Eduardo Rodriguez, Chris Sale). So it would help to have productive lefty bats, too, beyond Hicks, especially if Bird ends up in the minors, Gardner in a continued fade and Ellsbury on the DL — or else not pursuing Bryce Harper is probably going to become a greater issue.

Gregorius’ OPS vs. righties has improved in each of his Yankee seasons, up to .854 last year. The difference between Gregorius returning, say, June 1 or Aug. 1 is roughly 200 plate appearances, the preponderance vs. righty pitching.