It was June 13 in San Francisco, a typically chilly summer night with winds blowing in at AT&T Park, and standing around home plate was — surprise — professional golfer Dustin Johnson.

Well, maybe not so surprising. The night before, it was No. 1-ranked Rory McElroy — like Johnson, in town for that week’s U.S. Open at Olympic Club — who made a guest appearance for the opener of the Giants-Houston Astros series to throw the first pitch.

This night, it was the Columbia native’s turn to fire one to the catcher, a few hours before the Giants’ Matt Cain pitched a perfect game. The real pregame attraction, though, wasn’t the lanky, 6-foot-3 PGA Tour star demonstrating his big curve.

Earlier, Johnson (and several Giants, including Cain) had teed up golf balls and let fly over the leftfield wall into McCovey Cove. Giants’ officials measured several of Johnson’s “tape measure” drives at 330-plus yards, with one bomb of 335 yards.

Three months later, it was again Johnson’s propensity for the long ball that helped secure him a spot on the U.S. Ryder Cup team, which this week takes on its European counterparts at Medinah Golf Club near Chicago for the 39th battle for Samuel Ryder’s little gold trophy.

Maybe Dustin can squeeze in a trip to Wrigley Field?

“Obviously, I’m very excited to be on the team,” Johnson said the day U.S. Ryder Cup captain Davis Love III announced his four captain’s picks for the team. Also named were Jim Furyk, Steve Stricker and rookie Brandt Snedeker, a past RBC Heritage winner.

“I think I played well the last few weeks (before the selection) to make my pick pretty solid,” Johnson said. “I’ve played the Ryder Cup (2010) and The Presidents Cup (last year) away” in Wales and Australia, respectively, “so I’m really looking forward to playing one on U.S. soil.”

Nearly three weeks later, Johnson has not said much else about the Ryder Cup. Recently, citing a desire to focus on the FedEx Cup Playoffs and this weekend’s Tour Championship in Atlanta, he declined requests for an interview.

Instead, Love was left to assess his picks’ prospects, drawing fittingly on a baseball metaphor to make his point.

“It’s like (PGA Tour commissioner) Tim Finchem said about the Barclays: ‘It’s a big ballpark, isn’t it?’ ” Love said, referring to the first FedEx Cup Playoffs site — where, incidentally, Johnson tied for third.

“(Medinah) is (also) a big ballpark, and it’s perfect for us. I love Dustin Johnson on that golf course, and I really love our whole team on that golf course because we have a great driving team.”

Indeed, Johnson will enjoy a rare week not being the longest hitter on his team. That status goes to Bubba Watson, winner of this year’s Masters and one of the eight players who automatically qualified for the team.

Meanwhile, Johnson — who missed about three months of golf because of a back injury after he reportedly lifted a personal watercraft — finished 15th in the Ryder Cup points’ race and had to count on convincing Love in limited appearances. He did that by winning Memphis’ FedEx St. Jude Classic in his second week back and being the only player to finish in the top six in each of the three FedEx Cup Playoffs events (T-4 at the Deutsche Bank Championship and T-6 at the BMW Championship in addition to his Barclays showing).

The Deutsche Bank wrapped up Labor Day, a day before Love’s picks. But the captain said he already had Johnson on his radar.

“I was right near the lead the whole week at Memphis, and I watched him play a lot firsthand and, obviously, on TV, and hung out with him right after he had won in the locker room,” Love said.

“Dustin came back (from his injury) putting very, very well. He was hurt, couldn’t hit a lot of balls, but I think he putted a lot. He’s putted great since he came back at Memorial (where he tied for 19th) and has been putting very, very well.”

Putting has been the rap on Johnson as a Ryder Cup choice. In a pro-con article for golfchannel.com, writer Jay Coffin cited as pluses for the 28-year-old his length — “an advantage at Medinah” — and his strong season finish. For negatives, he noted Johnson’s rank of 89th in total putting, including 60th in the PGA Tour’s strokes gained-putting statistic, plus his mediocre record (2-6-1) in his previous two team-play outings; he was 1-3-1 at the 2010 Ryder Cup as a rookie.

Since Coffin wrote his article on Aug. 31, however, Johnson has improved his strokes gained-putting stat by 15 spots, to 45th. He can also point to his No. 7 scoring average (69.579) and, especially important in match play, his No. 18 ranking in par-breakers (21.87 percent).

As for his ability as a teammate, Love said he might have Johnson’s ideal foursomes or four-ball partner in Snedeker, one of the PGA Tour’s best putters. “I think they would be a good team together,” Love said.

“They both have come back from injury (and) they both came back right at big tournament time. (The) first tournament back for Dustin was Memorial; that’s not an easy golf course to jump back in on there, (and) he was top-20 there and won the next one. … You can’t argue with the golf that Brandt and Dustin have been playing.”

As for the ability to deal with Ryder Cup-style pressure, Love sees good omens in Johnson’s record in major championships, in which he has missed three cuts (most recently this year’s U.S. Open) in 14 attempts and had three top-10s. The other side might be Johnson’s infamous failures at the 2010 U.S. Open and PGA Championship and, to a lesser degree, the 2011 British Open.

Still, Love noted that Johnson had to put himself in those positions first before falling short. This year, he won a tournament and $3,188,060 despite his time on the sidelines.

“Being off during the year puts you a step back,” Johnson said, “but all of the events I played in this year, I played really well. I played solid, so I think I made my case (for selection) pretty strong. And I love playing team events.”

Now, the challenge is to prove he can produce points for a U.S. team that will be the underdog, even with a home-course advantage. Love thinks Johnson and the rest, on a course he believes favors them, can do enough to end a six-losses-in-eight-meetings skid dating from 1995.

“Medinah (is) a big, long golf course that’s going to have fast greens, and it’s going to look like a major championship,” Love said. “I think a lot of guys on our team are really used to that kind of golf.”

Long ball? Yeah, Johnson knows that game.