The Brewers' 11th-round pick in last week's First-Year Player Draft, Gainey had to choose between the security of a career in the Navy and the potentially higher-paying profession of baseball player.
Gainey showed he believes in his baseball ability, which is why he signed with the Brewers on Tuesday night.
"My whole goal is to make it to the big leagues," said Gainey, 21. "It's a full-time job, and I am going to work my tail off."
The move means that, in all likelihood, Gainey's career as a Navy officer is over. The Naval Academy is not like a typical university, where you can just sign up for classes.
Then again, had Gainey chosen to return to Navy for his junior season, he would have had to sign up for two more years of school and five years of military service, effectively ending any realistic chance at a big league career.
"I tossed and turned over the decision for an entire week," Gainey said. "It was a back-and-forth deal. Do I leave the Academy, where I have a great education and a lot of friends? Or do I follow my dreams and play pro baseball?
"Ultimately, I felt God was calling me to play pro baseball."
Gainey would not disclose his signing bonus, but sources indicated the deal was somewhere north of the $100,000 slot, including provisions for the two years of college he needs to complete his degree in economics.
Interestingly, it was Gainey's knowledge of economics that had him tossing and turning. A career in the military would pay about $70,000 to start, with salary bumps as he rises up the ranks.
The money in the Minor Leagues is very low in comparison. But if Gainey makes it to the Majors, he could strike it rich.
Money aside, Gainey had wanted to serve his country as three of his relatives -- including two of his grandparents -- had done previously. But the opportunity to play pro baseball has long been his dream.
Gainey plans to travel to the Naval Academy in Annapolis, Md., later this week to begin the process of withdrawing from school, which could take anywhere from four to 10 days.
Once that is cleared up, the 6-foot-3, 205-pound right-hander, who went 3-3 with a 3.25 ERA in 10 starts as a Navy sophomore after going 2-0 with a 3.00 ERA and four saves out of the bullpen as a freshman, can begin his pro career.
Navy coach Paul Kostacopoulos said Gainey, like most Navy players, was not highly recruited when he decided to come to Annapolis.
"But you could see if a few things fell into place, he could be special," Kostacopoulos said of Gainey, who played his senior year of high school at Calvary Christian in Fort Lauderdale, Fla.
"He's a power pitcher and a vicious competitor. He really had a breakthrough this year."
Kostacopoulos said Gainey throws his fastball in the low 90s. The coach also said Gainey has an "electric slider" that reaches 80-82 mph.
It's an appealing combination, which is why Gainey said the Brewers started calling him in the fifth round, telling him to be ready. Negotiations came into play, as they always do with Draft picks these days, but there was no question the Brewers were interested.
"They flew him out for a pre-Draft workout and really liked him," Calvary Christian coach Gregg Mucerino said. "He has a passion to play baseball.
"He's the hardest-working pitcher I've ever coached. He's a determined guy who believes in his stuff. His mechanics and command have gotten a lot better the past couple of years.
"If he stays healthy, he has the body and the work ethic to be special."
Walter Villa is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.