COOPERSTOWN — Aside from having been great baseball players who forever will be linked by entering the Hall of Fame together this year, Ken Griffey Jr. and Mike Piazza have one thing very fundamentally in common. They both absolutely love to play golf.

Both played in the Hall of Fame Invitational Saturday morning, a tradition that reportedly began with an intense match between Babe Ruth and Ty Cobb at the inaugural induction. In a way, the tournament is an indoctrination. For the soon-to-be inductees, it is their first official act as Hall of Famers because they compete against players who were enshrined ahead of them.

Griffey always has had close golf ties. He is a former Orlando-area neighbor of Tiger Woods and is said to have allowed Woods to stay in his Seattle house during a tournament. Griffey is so serious about his own game that when Sports Illustrated interviewed him about becoming a Hall of Famer, he repeatedly refused to be photographed taking a baseball swing because, he admitted later, it would mess up his golf swing. He also insisted that the magazine say he is a 13 handicap, while he actually is a 3.

He played in a pro-am before the Women’s PGA this year and was in a group with top-ranked star Lydia Ko, who said afterward, “Ken hit the ball a mile. And actually hit it really straight.”

Piazza has said that his Dodger buddy Eric Karros — whom he invited to play in his foursome yesterday — used to joke that the only athletic things Piazza can do are hit a baseball, throw a football and hit a golf ball. The Mets great told golf.com that his clubhead speed has occasionally been measured at PGA Tour levels.

When he was asked during his round about the state of his game, Piazza said, “It’s been better. It’s been tough because I was just in Europe for a few weeks and I haven’t played that much. But it’s always good to be out here.”

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The point is, baseball and golf are and always have been a good pair (as Yoenis Cespedes can attest, as he likes to play in the morning before Mets night games). In the Hall’s Babe Ruth room, there are numerous golf trophies and other mementos.

Many of the Hall of Famers, their competitive natures still burning, play a lot of golf and are quite good about it. They like to downplay how good they actually are. When Rollie Fingers was asked yesterday what his handicap is, he said, “Golf!” Then he did admit to holding a very admirable 7, but he nodded toward his son Jason, saying, “He hits it 30 yards past me.”

Carlton Fisk also is a single-digit golfer. “If the putter works,” he said as he headed down the first fairway (his ball was right in the middle). “On this course, the putter never works.”

Griffey appeared very relaxed a day before having to make his acceptance speech. He said, “The golf game is OK.” Someone asked him about a rumor that he had actually shot 1-over par the previous day and he said, “That’s just a fabrication.” Then he went to the first tee box and launched a huge drive down the left side of the fairway.