At first glance, he's just a face in the White Sox' media guide, right there on Page 16, under the vague banner of Baseball Operations:
Major League Coach
The Sox may have opted for the brief notice to save on printing costs, but Gellinger, a 1982 Fremd High School graduate, has done nearly everything possible at every level and evolved into so much more than a major-league coach for the White Sox.
Just ask manager Ozzie Guillen.
"I love him," Guillen told the Daily Herald before Thursday's home opener against Tampa Bay. "I love him so much that if Joey (Cora) got the managing job (with Milwaukee last winter), Gelly was going to be my new bench coach. That's how good he is, that's how much I trust him. He's done a lot of great stuff for the White Sox."
Growing up in Palatine, Gellinger got his baseball career started while playing for his legendary father, Terry, at Fremd.
"That's all we did was baseball," Mike Gellinger said. "He would always ask, 'Do you want me to throw you some batting practice? You want me to hit you some grounders?' He loved baseball, and that's how I grew up. He pitched at (The University of) Illinois, and he actually pitched in the Pan-Am Games in 1959 before he tore his rotator cuff."
Terry Gellinger was Fremd's baseball coach for 30 years and he guided the Vikings to the state tournament in 1979 and 1984. In '97, he was voted into the IHSA Hall of Fame.
Mike, meanwhile, finished his prep career at Fremd with the most doubles (22) in school history, a record he still shares. He also ranks among all-time leaders in batting average (.388), hits (83), runs (69) and triples (5).
After that, it was off to Southern Illinois University for three years as a second baseman, semipro ball in downstate Maryvale, and then a big break.
"I never was drafted, but a Detroit Tigers scout saw me in Maryvale and offered me an opportunity," Gellinger recalled. "I took it."
That led to a year of Class A baseball in Gastonia, N.C., before he was released.
Determined to give it one more shot, Gellinger headed to Florida the following spring to pursue a minor-league job with the Baltimore Orioles.
"I ran into Doug Rader in Stuart, Fla., where my grandparents lived and his kid was playing on a team I used to throw batting practice to," Gellinger said. "Rader threw me batting practice one day and said, 'Let me make a phone call for you.'"
Rader had ties with the organization and in 1987 Gellinger went to the White Sox' minor-league camp and made the Daytona Beach club in the Florida State League.
He's been with the organization ever since.
"Halfway through the season at Daytona Beach, I got sent to Hampton, Va., in the Carolina League and finished the season there," Gellinger said. "I didn't do too bad."
But Gellinger's days as a player basically ended the next year when he was 23. Not that it was a bad thing.
"In the winter of 1988, the White Sox made a decision to hire four player/coaches," Gellinger said. "So they hired me. I was a player/coach in the Florida State League. Al Goldis made the decision, and they also hired Tommy Thompson, (former Sox hitting coach) Ron Jackson and Eddie Sedar, who's now the third-base coach with the Milwaukee Brewers."
Gellinger went from player/coach to managing the Sox' Class A team in Utica (N.Y.) and coaching five more years in the minors.
So how did he eventually land with the White Sox?
"In 1997, I got the job here as computer scouting analyst," said Gellinger, who admits he grew up rooting for Robin Yount, Paul Molitor and the Brewers. "I charted our own games with a pencil and paper. It was put into the computer and then it could spit out any information on the White Sox they wanted, pretty much. It's come like 9 million miles since then."
And so has Gellinger.
He is still the Sox' computer scouting analyst, but Gellinger has evolved into hitting coach Greg Walker's top assistant.
"I've had my best years with the help of Walk and Gelly," White Sox first baseman Paul Konerko said. "Those two, they listen to you, they offer advice and they really know how to break it down."
Said Walker: "Gelly is much more than another pair of eyes. He's been invaluable."
Quiet and humble, Gellinger is not looking for any credit. He's just thrilled to be a longtime White Sox employee.
"I've always been in the (indoor batting) cage throwing the guys flips," Gellinger said. "There are times when Walk is busy or working with someone else, so I'm always available if guys need help. It's worked out great."