It was a tantalizing day of wondering what might have been for Jeff McNeil.

Don’t, however, misconstrue that as it being a day with even a nanosecond of regret for the Mets’ sweet-swinging Mr. Versatility, who happens to be leading the major leagues in batting with a .339 average.

“This,’’ McNeil told The Post as he stood off to the side of first fairway at Liberty National on Thursday watching Tiger Woods hit an approach shot into the green, “is always what I wanted to do.’’

If not for being ignored by college coaches, McNeil might be roaming the fairways of Liberty National this week chasing the $15 million FedExCup Playoffs pot of gold.

Thursday’s visit to the opening round of the Northern Trust on a Mets day off as they brace for this weekend’s home series against the Nationals was McNeil’s first time at a PGA Tour event — other than one Masters practice round when he was a kid.

As much as it stirred the passion he still has for golf, there was little question McNeil would much rather be chasing a playoff berth and a batting title than chasing little white dimpled balls around the world’s best golf courses against the world’s best players.

He doesn’t take his magical and unlikely ride for granted.

“To be doing what I’m doing,’’ he said, “is kind of surreal.’’

As much as he relished Thursday’s “what-if’’ visit to Liberty National and craves his time on the golf course, McNeil hardly could contain himself at the thought of weekend’s series against the Nationals at Citi Field.

“The energy at the ballpark is going to be just like Opening Day,’’ McNeil said. “I know New York will show up. It’ll be loud and it’ll be fun. The Yankees are already in the playoffs. It’s boring now [because they’re so dominant]. Now it’s our turn to do our thing and get the city behind us.’’

As he surveyed Woods in the third fairway, McNeil was asked about his former peers from his junior golf days.

“It’s pretty cool to see a bunch of the players I played against in junior golf out here — Jordan Spieth, Patrick Cantlay, Daniel Berger, Patrick Rodgers,’’ McNeil said. “In my head, I’m like, ‘Yeah, I played with these guys before, this could have been me if I stuck with it.’ If I went to college and played, you never know what might have happened.’’

But what McNeil has done in his short time with the Mets has made it easy for him to never look back.

Does he miss golf?

“Yeah, all the time,’’ McNeil said. “I’ll still play tournaments in the offseason — any amateur event I can get into. I spend every off day during the season playing. It’s like a getaway for me, a mental break from baseball.’’

McNeil’s father, Steve, got him into the game, brought him to a par-3 course when he was a kid growing up in Nipomo, Calif.

“Every weekend, we used to play golf and come home and watch Tiger win tournaments, because that’s what he did when I was a kid,’’ McNeil said. “That’s what got me into it.’’

McNeil became an accomplished enough golfer as a teenager that he had legitimate aspirations to be a professional golfer. He considers his greatest golf accomplishment when he qualified for the U.S. Junior Amateur Championship in 2009 at Trump Bedminster in New Jersey.

Spieth — whom McNeil met with briefly before Spieth’s afternoon tee time Thursday — won that U.S. Junior Amateur and now owns three major championships.

“I remember I was on the range the day before the [U.S. Junior Am] in the practice round and Spieth came right up next to me and hit balls,’’ McNeil said. “I remember just stopping and watching and going, ‘Oh my God.’ Just seeing him hit the ball was incredible. I was just more in awe.’’

Baseball for McNeil, back then, was secondary.

The catalyst to his career transition from golf to baseball was the result of him being ignored by college golf coaches as he sought a scholarship. Just 17, he joined his younger brother’s baseball team and played well enough that the coach asked him, “Do you want to play college baseball?’’

“I said, ‘Yeah, sure, I’m not getting any calls from colleges for golf,’ ’’ McNeil told the coach.

He ended up playing college ball at Long Beach State and, after six years in the minor leagues, the Mets called him up last season and his batting average has been well north of .300 ever since.

“I could have walked on just about anywhere to play golf, but they weren’t offering scholarships,’’ McNeil said. “I ended up getting a baseball scholarship, and it paid for my school.’’

For McNeil, who still owns a scratch handicap, it’s ended up paying for a lot more than school. As much as those former peers of his competing at Liberty National on Thursday are stars in their sport, McNeil is a baseball star now. And that’s perfectly fine with him.