And the gifted center fielder from Vancouver, British Columbia, has sped himself not only into top prospect status but also into a slot representing the Mariners on the World Team at the upcoming XM All-Star Futures Game.
"I was so surprised, I hadn't been thinking about it at all," said Gillies, who was hitting .328 with an organization-best 23 steals for the Advanced A High Desert Mavericks. "When I got the call, I was really happy."
The 11th annual XM All-Star Futures Game, pitting the best Minor League prospects from the United States against the best from the rest of the World, will be held at Busch Stadium in St. Louis on All-Star Sunday, July 12, at 1 p.m. CT. MLB.com will provide complete coverage before, during and after the game, which can be seen live on ESPN2 and ESPN2 HD and followed live on Gameday.
Gillies, 20, has been opening eyes and creating big-time buzz in his first full season with the Mavericks, ranking among the California League leaders and even, in a few cases, overall Minor League leaders in several categories.
And he's done it against the odds.
Not just because he wasn't drafted until the 25th round of 2006, signing the next spring as a draft-and-follow out of Iowa Western Community College. That alone might be a hill to climb when pitting the left-handed hitter up against high-round picks and international bonus babies.
At age 4, Gillies was diagnosed with a hearing impairment that has left him with 30 percent hearing in one ear and 60 percent in the other.
Thanks to the use of hearing aids and an ability to read lips that he learned before his impairment had even been diagnosed by doctors, though, Gillies has not let what some would view as a "disability" stop him, on the field or off of it.
"Really, I haven't found any negatives at all," said Gillies. "I know that sometimes coaches may think that when I have my helmet on it can be a problem when they're yelling to me, but I think baseball is more hand signals than anything so if you really know what's going on, you don't have to hear much in this game."
And it certainly hasn't affected his play or his prospect status in any ways but positive ones, such as the remarkable focus with which he plays and the makeup that has allowed him to rise to the top so rapidly.
"Because I can't hear, I have to view everything in my head before it happens," he said, "and know how to react in every single situation."
The Mariners have not had to make many adjustments or modifications when it comes to Gillies.
"He's so good at what he does that you don't have to," said Seattle player development director Pedro Grifol. "The only adjustment everybody makes is that when you speak to him, you make sure to look him straight in the eye and maybe slow down a little."
In his first full season, Gillies has exploded onto the prospect scene as he helped lead the Mavericks to the first-half title in the South Division of the California League, marking the first time the Mavs have won a first-half title in the league since 1993.
Gillies was among the league leaders in batting, steals and runs scored, as well as ranking among the Minor League leaders in triples.
Adept at doing "the little things" well when it comes to getting on base, with a .434 clip also among the best in the Minors, he also ranked among the tops in sacrifice hits and even getting hit by pitches.
But it's his world-class speed, ranked at a scouting-scale best 80 (on a scale of 20-80), his range in the outfield, his strong arm that allows him to play all three positions if needed and his live bat that make him such an exciting player to watch.
His performance thus far, despite having skipped right past Class A Wisconsin, has been gratifying to the Mariners but not all that surprising.
The decision to send the 20-year-old right from short-season Everett, where he was the AquaSox team MVP in 2008 after hitting .313 with 24 steals, to High Desert was one that was a hot topic of conversation during Spring Training but one hailed unanimously by the Mariners' player development staff.
"The reason is because here we've got a kid who is so talented with so many tools, but he had two in particular that really dictated that he could make the move and it would work," said Grifol. "One was hand-eye coordination and the other was speed. When you have the hand-eye coordination, you'll make contact, and when you have speed you'll rarely go into a prolonged slump."
Gillies' .313 average in 17 games as a non-roster invitee to Mariners Spring Training certainly helped his case, but it was his overall package, both physical and mental, that sealed the deal. "We were all convinced it would work, it wasn't like there were one or two guys who were fighting it and I had to make the final decision," Grifol said. "Everyone felt he could do it. And with High Desert being in a good hitters' league, we felt this might be one of the rare times where you jumped a prospect to a level where he could succeed and be ready for Double-A by the following year. It was unanimous."
Gillies' first half has confirmed the team's instincts as he becomes the third Canadian prospect in as many years to represent Seattle in the Futures Game, following in the footsteps of pitcher Philippe Aumont in 2008 and outfielder Michael Saunders in 2007.
"We felt he'd be strong enough mentally to overcome any obstacles," Grifol said. "His makeup, his ability to apply instruction at a rapid pace and his athleticism make him such a special player."
Along with the speed and defense, Gillies has hit for a .305 average since his 2007 pro debut and while he had hit just two homers coming into 2009, he already had six in the first half of the season, including a pair of two-homer games.
Add in the sixth intangible tool of makeup and ask for a current Major League player comparison, and Grifol hesitates for a moment.
"I don't like throwing big league names around in comparison to Minor League players because guys who are big leaguers have earned that respect," he prefaced. "But (Mariners special assistant to the GM) John Boles and a lot of others have compared him to (Detroit Tigers star) Curtis Granderson because that's the kind of kid we think we have here. And of course that would be tremendous for this organization. He has that type of physical potential and that type of makeup. "
In the meantime, as Gillies heads off to St. Louis with High Desert teammate third baseman Alex Liddi, the organization could not be prouder or more delighted.
"It is so great to see a kid like this be rewarded and to represent the organization in his type of venue," said Grifol.
Lisa Winston is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.