He quickly jumps up, gathers some loose equipment and heads to another part of the park to continue his pre-game routine.
It's more than two hours before Wallace's Las Vegas 51s take on the visiting Iowa Cubs, but the lefty-swinging power hitter is diligent in his preparations.
The work isn't limited to the cage for this 23-year-old first baseman.
The top position-player prospect in the Blue Jays system, Wallace was batting .288/.348/.565 through 170 at-bats. His 11 home runs paced the Pacific Coast League, while his 33 RBIs ranked fourth. The power numbers and offensive potential, however, aren't the lone criteria for a likely callup to Toronto later this season.
Even more impressive than Wallace's early season slugging was that he had made just three errors at first base and had shown other signs of defensive improvement.
"I've shown a consistent approach in what I can do, and that is being a complete player," Wallace said. "I'm real focused on showing that I can play first base because I know what is ahead of me when I'm ready."
It hasn't come without logging extra hours, which is something he's become known for in quickly earning the respect of coaches and veteran teammates.
Wallace devotes time every afternoon, hours before first pitch, to fielding plenty of groundballs and participating in other drills aimed at mastering his new position.
Who's On First?
The 13th overall pick in the 2008 draft, Wallace started his professional career as a member of the Cardinals, and as a third baseman.
But following a pair of high-profile trades, he's now on the other side of the diamond, where he stands poised as the heir apparent to Lyle Overbay in Toronto. In the final year of his contract, Overbay's bat remained in a deep freeze at baseball's one-quarter mark.
Just don't tell Wallace he's a shoe-in for a long big league career. The Arizona State product, who won two Pacific-10 Conference triple crowns, is very diplomatic in his approach: Nothing, no matter what is written or said, is guaranteed.
Hence, the hard work.
"We are taking baby steps with him (defensively)," Las Vegas manager Dan Rohn said. "You have to give him credit. He is willing to work at it."
Wallace played first base for half of his three-year career at ASU, and while the pro game has its subtle differences, the familiarity has helped accelerate the adjustment process.
It's a process Wallace admits has taken time away from his offensive approach. He has shortened part of his pre-batting practice work—now taking 10 swings off the tee and 10 soft-toss cuts—to allocate more time for defensive drills.
He previously would take 100 swings off the tee, but Wallace credits 51s hitting coach Chad Mottola for developing a more economical program he easily found comfort with.
The end result hasn't changed from his initial two pro seasons. Last season, while playing for two organizations, Wallace batted .293/.367/.455 with 20 home runs and 63 RBIs in 532 at-bats, spent mostly at the Triple-A level.
In July, St. Louis made Wallace the centerpiece of its trade with the Athletics for Matt Holliday. The trek from Memphis to Sacramento served Wallace well. In his final 44 games with the River Cats, he ripped nine of his homers and slugged .505.
Undaunted By Expectations
Wallace reached Double-A in his first year of pro ball, batting .337/.427/.530 in 202 at-bats along the way. "The big thing for me is having fun with it," he said. "I'm in a great spot. I love what I'm doing."
Wallace has developed thick skin in his approach. After all, not many first-round picks are traded twice before they reach the big leagues. Just five months after acquiring him, the A's flipped Wallace to the Blue Jays for outfielder Michael Taylor, who had been acquired when Toronto traded Roy Halladay to the Phillies.
Any player of Wallace's pedigree and potential would surely question why one franchise would so quickly give up on his services. Then again, they were high-profile trades for two of the game's best players.
Like everything Wallace does, his approach to the trades has been positive. And being with the Blue Jays is an ideal spot for a prospect, he said.
"We are going with our youth and building from within the system," Wallace said. "That is something you want to be part of. That's a good spot for some to be in. Now, I just have to be more consistent and continue working to prove I deserve a chance."
It's that type of attitude that coaches say has helped Wallace adjust to the expectations that come with his past accomplishments. He doesn't waste an at-bat, an inning in the field or a pre-game workout.
"He has the type of power you can't teach," Mottola said. "And he doesn't try to force his power. He knows that when you go up looking for a home run, that will get you in trouble."
Wallace also knows Toronto general manager Alex Anthopoulos is closely monitoring his progress. But like everyone else, he has no idea when he'll get his shot at the next level.
Some reports say it will be in September when rosters expand, while others speculate it could be sooner to give the Blue Jays' offense a spark.
Just don't expect Wallace to spend too much time worrying about it. He's too busy making himself the best first baseman possible and polishing his skills at the plate.
Ray Brewer covers local sports for the Las Vegas Sun