Kelly stays on the field for 10 or 20 seconds at a time. He has one job: win faceoffs.
His success garnered the attention of the country's premier college programs. He is ranked by InsideLacrosse as the nation's eighth-best prospect in the Class of 2015.
With possession of the ball so critical in the sport, college coaches realize how important a faceoff specialist is.
Kelly committed to North Carolina before his sophomore season, and he likely will start his freshman season as the Tar Heels' faceoff specialist.
He realized in eighth grade that his skills were not quite cut out for playing at Malvern, one of the area's perennial powerhouses. So he started to specialize in faceoffs.
Most teams have a specialist, which is known in lacrosse circles as a FOGO. The acronym stands for "Face Off, Get Off."
The faceoff is unique to boys' lacrosse, as girls' games use a draw to resume play. Two girls stand at midfield and shoot the ball in the air before trying to recover it.
After a fall clinic with the Duke's Lacrosse Club, one of the area's top programs, Kelly approached assistant coach Mike Dolente and asked if he would teach him the art of the faceoff.
Dolente, who was a specialist at Cabrini College, agreed. Kelly challenged him right away to a faceoff. Dolente declined at first but finally obliged, warning his new pupil to be careful. Kelly was wearing his helmet; Dolente was not.
Kelly failed to follow the warning, dove for the ball, and cracked his coach's nose with his helmet. Dolente said he still managed to win the draw.
The two worked out privately and, Kelly said, Dolente became his mentor. Kelly also attended his coach's Philly Faceoff League, which Dolente started last winter with John Bodnar, another former Cabrini faceoff specialist.
The group hosted weekly sessions with roughly 40 of the area's top specialists. The players spent 90 minutes practicing their techniques against one another.
Kelly mastered his stance and used his quick hands. Malvern assistant Todd MacFarlane said Kelly worked hard in the weight room and added strength.
Kelly spent his freshman season watching Malvern's P.J. Finley, now the faceoff specialist for Notre Dame.
Dolente said Kelly's fiery and competitive personality is perfect for taking faceoffs, which he said is an individual aspect of a team-oriented sport.
"You have to have an 'I'm-the-man attitude and no one can stop me,' " Dolente said. "As soon as you lose that, you lost."
Kelly is on the field about 20 times per game. A faceoff takes place at the start of each quarter and after a goal is scored. The more times Kelly wins a faceoff, the more possessions Malvern earns. More possessions equals more chances to punish an opponent.
The referee places the ball at midfield, and a player from each team crouches next to it. The two place their sticks near the ball and await the referee's whistle.
Once the whistle blows, the players try to snatch the ball with their net. They are not allowed to use their hands deliberately or grab the other's stick.
Kelly is a "clamper," as he tries to cover the ball with his netting and clamp it against the turf. He can scoop up the ball and run, or ditch it to a teammate waiting on the wing.
Kelly said he gets as low as possible without his knees touching the ground. This allows him to use his leg strength and quickly get himself out of the circle once he wins the ball.
The faceoff exchange is sometimes so quick that Kelly will emerge with the ball while his opponent is still searching for it.
What's his secret?
"I can't tell you that," Kelly said.
Malvern was tied with Episcopal Academy earlier this week, and the overtime was about to begin with a faceoff. Kelly ventured toward the circle as he always does, a slow walk with a bit of swagger. He carried his stick in his right hand, tugged on his metal face mask with his left.
The opponent usually runs to the circle, beating Kelly there. Possession is not awarded for being first to the circle, but for being first to leave it.
And Kelly tends to leave more quickly than most.