He arrived at Castlewood Country Club in 1986, right into a period when a number of the youth golfers would evolve into the professional ranks.
Young men who developed legendary status on the links by the time they went away to college included players like Todd Fischer, Joel Kribel and Bryan Pemberton, and young ladies such as Paula Creamer, Jean Zedlitz and Ashley Gomes, left their marks in the junior golf circles of Pleasanton. Most have gone on to play professionally at some level.
The common ground for most was the Castlewood Country Club Junior Merit program where some long-time members still talk about the exploits of Fischer and Pemberton.
"We had a nice, organized program," said Fischer of the junior club at Castlewood. "There were a lot of really good players in a little area."
It did not take long for O'Leary, now an instructor at the Pleasanton Golf Center, to know how good some of the young golfers were playing.
"I got there when they were around 15 or 16," said O'Leary of Fischer and Pemberton. "They were already unbelievable. They could only get out on the course at certain times so they spent hours chipping and putting."
When they did get on the course, oftentimes their success came at the expense of members or visiting junior teams.
"Those matches were a lot of fun," said Fischer with a hint of nostalgia in his voice. "No one came to the Hill (course) and beat us."
After a stellar career at Foothill, Fischer played at the University of San Francisco before turning professional in 1993; to this point he has $2.8 million in career PGA Tour earnings, with four career third-place finishes in the Greater Hartford Open, the Reno-Tahoe Open, the B.C. Open and the Valero Texas Open.
In 2002 while on the Nationwide Tour, Fischer won the Fort Smith Classic on the way to finishing seventh on the Nationwide Tour money list. The success of the season earned Fischer a spot on the PGA Tour where he played full time from 2003-06.
Highlights along the way included a hole-in-one on the 7th hole at Pebble Beach in the second round of the U.S. Open in 2000.
At 42 now, Fischer is in some sort of limbo waiting to turn 50 and take a shot at the Champions Tour. Until then, it will be about getting sponsor exemptions to get into tournaments or occasionally playing in a Monday qualifier hoping to earn a spot in the field.
Fischer recently qualified for the TPC Stonebrae Nationwide event where he made the cut and finished in the middle of the pack. When not playing, Fischer is busy with his family life and his kids.
Through it all, Fischer remains confident about his game.
"I think I am better now than I was when I was younger," he said.
Kribel turned pro in 1999 after finishing at Stanford and a prolific amateur career. Kribel, who was a four-time All-American at Stanford, played on a Walker Cup team and was twice a member of the World Am team.
In 1997, Kribel was the runner-up to Matt Kuchar in the U.S. Amateur, falling 2-and-1 at Cog Hill. In 1996, Kribel fell 3-and-1 to Tiger Woods in the semifinals of the Amateur as Woods was on the way to his final Amateur title.
"The Amateur is the tournament of the year before you turn professional," said Kribel. "You circle the tournament on your calendar each year."
Kribel's first inclination he was on track to become a professional came earlier in his career. One year in the Junior World tournament in San Diego he turned in a solid effort against a field that included Woods and several other future professionals.
"I was 16 or 17 and played really well in the (Junior World)," said Kribel. "At that point I felt I could hold my own."
Kribel was an accomplished athlete in a number of sports, trimming down to baseball and golf as he got into his teen years.
"I always had the dream to play a professional sport," said Kribel, an ambition shared by a number of young athletes. "There seemed to be more baseball players that were better than me than there were golfers. I always enjoyed both sports, but I knew golf was my best shot."
Now 35, Kribel has been battling a myriad of health issues throughout his professional career. It started when he was a rookie on the Tour and fractured his finger; later it was a bad back, the worst physical ailment a golfer can face.
Kribel's competitive nature has kept the juices flowing and the positive approach may be paying off.
"It's been seven to eight years since I have felt this good," he said. "I had a stretch for years where I felt bad every day. This year I had one little stretch where it was bad. I still have kinks to iron out, but I am closer than I have been in a while. If I can stay healthy, I can dig myself out and get back to where I am competitive."
There is another former Pleasanton youngster who didn't play golf until later in life but has advanced to the professional ranks as well in Dean Vomacka.
Vomacka is an interesting story as he didn't pick up golf until after he graduated from Foothill. An all-league basketball and baseball player, Vomacka decided to give golf a go.
Through hard work Vomacka has qualified in to some PGA Tour events, including the Waste Management Open and the Frys.com events. Now in his early 40s, Vomacka, who has worked as a golf professional at some clubs in Arizona, is still playing in some mini-tour events in hopes of making it full time on the PGA Tour.
Bryan Pemberton was a star at the University of Southern California and has spent a lot of time as a professional at clubs throughout Northern California.
Paula Creamer is the most accomplished of the local talent lot, winning the Women's U.S. Open in 2010 and becoming one of the more recognizable golfers in the world, but Jean Zedlitz was the trailblazer for females from Pleasanton.
Zedlitz was the oldest of the group and O'Leary got a dose of her talent early on as well. At the time there was no girls' golf at the local high schools, so Zedlitz played with the Amador Valley boys' team.
"I remember hearing Amador was playing a match down on the Valley Course (at Castlewood) and that they had this girl who was an incredible player," said O'Leary. "I got in the cart, went down and watched two holes. On the par 5 she was just off the green in two. That was all I needed to see."
Former Las Positas pro Dan Lippstreu worked with Zedlitz starting when she was 12 or 13 and could tell right away she was a player.
"We would meet once a week and it was more like a supervised practice session," explained Lippstreu. "Jean was not just a great golfer, but she was a great athlete as well. She was probably the most talented golfer I have ever worked with."
Zedlitz didn't just play for the boys' team at Amador Valley -- in fact, she was the No. 1 player at Amador and among the elite players in the league. She even took it further than being the best player at the high school.
"I remember I got a call from her after the East Bay Athletic League tournament and I asked her how she did," said Lippstreu. "She told me she had the best score and I assumed she meant she beat the other girls. But she said she shot a 71 and beat everyone. She went out and beat all the boys as well."
After high school she went on to UCLA and was a two-time All-American. After turning professional in 1993, Zedlitz played for several years on the LPGA Tour.
Born in 1986, Creamer started playing golf when she was 10 and within two years, she was among the elite junior golfers in the country.
In 2003 and 2004, Creamer was the top ranked amateur and in 2003 was named the American Junior Golf Association (AJGA) Player of the Year. She ended up winning 11 AJGA tournaments and she was a member of the 2004 U.S. Curtis Cup team. She also represented the United States in the 2002 and 2003 PING Junior Solheim Cup matches.
Along the way, Creamer left Pleasanton and moved to Bradenton, Fla., just before her freshman year in high school to attend the prestigious IMG Academy, immersing herself in golf.
Once she turned professional in 2005, Creamer wasted little time in making her mark, winning the Sybase Classic just four days before graduating high school and then the Evian Masters later in the year.
Creamer has won nine times on the Tour and has almost $9 million in career earnings. In 2010, Creamer won the Women's U.S. Open, the crowning achievement of her career so far.
Creamer has become one of the faces of women's golf and one of the more popular players with young girls around the world. In 2009, Creamer was named co-chair of the First Tee's Young Ambassador Council.
Ashley Gomes -- now Ashley Kettmann after getting married to long-time boyfriend Jeff -- has had her time in the television spotlight after starring in a pair of the Golf Channel's Big Break competitions. A former star at San Jose State following her time at Foothill, Gomes spent several years as a touring professional.
Now 30 and expecting her first child in August, Kettmann is back in Pleasanton and running women's golf programs at the Pleasanton Golf Center, founding a program called "Queens of the Greens." She also works with former LPGA Tour player and Southern California superstar Dana Dormann who now also lives in Pleasanton. It was players like Dormann (Dana Lofland before she was married) and Zedlitz that set the path for Kettmann.
"I always looked up to Dana and Jean," said Kettmann, still displaying the same personality and charm that made her a fan favorite on Big Break VII, where she advanced to the final two before losing to current PGA Tour player Tommy "Two-Gloves" Gainey.
Kettmann looks back fondly on her junior years, having spent some time honing her skills at Castlewood alongside Creamer. She also recalls having Fischer and Pemberton work with the junior players when they were in high school.
"Todd hit a fade and Bryan a draw and they used to make their balls hit in the air," said Kettmann. "That was pretty amazing."
Now that she works with junior golfers, Kettmann has seen a big change in the game.
"The girls are so serious right now," said Kettmann about today's junior golfer. "They don't seem like they are having any fun. Some of the parents are crazy now."
It has been a great run for the junior golfers of Pleasanton and there figures to be more to come.
"I think you will see something again," said O'Leary. "There are so many good, young players in Pleasanton."