The Data Behind the Decision
How Joey Kalbas, Director of Data Analytics at a D1 Tennis Program, stopped guessing and started knowing
SETTING
NCAA Div. 1 Tennis
PRACTITIONER
Joey Kalbas
RANKING
Top 10 nationally for over a decade
ROLE
Director of Data Analytics
A sport that outpaced its own monitoring
Joey Kalbas' program didn't lack technology. Two years ago they brought on Catapult, a GPS-based platform that gave them a meaningful window into how tennis players move. It was a step forward. But tennis has a way of humbling even well-designed systems.
THE GAPS
Per-side data
Catapult captured whole-body movement. What the staff needed was per-leg data — the difference between symmetrical effort and quiet compensation.
Indoor continuity
GPS doesn't work indoors. Half the spring season is played inside — meaning half the season's data was simply missing.
“Our biggest challenge was finding a way to use the same metrics every single day, no matter where we were.”
The data stream had gaps. And in a sport where individual player health can swing a team's seeding, ranking, and tournament fate, gaps are expensive.
The entry point: one athlete, one season
Plantiga entered through a single player — a decision that felt low-stakes at the time but proved to be a proof of concept for the entire program. The athlete had a history of knee injuries. Two consecutive seasons had ended early because of them.
“We wanted a very good sense of — hey, is this player leaning more towards her injured side? Maybe this is a good weekend to sit her down.”
The goal wasn't to sideline her. It was to make informed decisions rather than reactive ones — to use data to separate fatigue and asymmetry from genuine injury risk before it became a real problem.
WHAT CONVINCED THE PROGRAM TO EXPAND
Out-of-the-box dashboards that the coaching staff could understand immediately
Continuity indoors — the same metrics available every day, regardless of venue
Per-leg asymmetry data that GPS-based tools couldn't provide
A clear proof of concept before the team moved indoors for the spring season
The moment that mattered
The team was scheduled to play a rival on Friday and the number-one ranked team in the country on Sunday — with national championships the following week. The Friday match was grueling. A player who already had a lower body injury appeared to aggravate the other leg.
The consensus was almost immediate: rest her. Protect her for nationals. Don't risk a long-term asset for a single match.
But Joey and the program's athletic trainer looked at the jump test data first.
“Her data looked exactly like we would expect from any other player the day after a match. We presented the coaching staff and said: we believe there is no increased risk from her playing on Sunday.”
WHAT HAPPENED NEXT
She played. The team won — defeating the number-one program in the country.
That victory wasn't just a result. It was a seeding. Winning placed them in the driver's seat for a top-8 national seed, which could mean hosting the first three rounds of the NCAA Tournament.
“If you take that win out, we would have been fighting tooth and nail to get that top-eight seed.” A single data-backed decision reshaped the entire postseason picture.”
What's next: movement, biomechanics, and the unexplored
Joey's vision for where this technology goes is as specific as it is ambitious. The foundation is already in place — now it's about deepening what the data can answer.
“If you can integrate it with video — look at when a player is going into and out of a groundstroke or a serve, look at how their legs are moving — you start to ask: is one leg not moving fast enough relative to the other, and is it causing them to hit a weaker ball?”
THE NEXT FRONTEIR
Video integration — linking lower body asymmetries to stroke mechanics in real time
Biomechanical standards — defining what an optimal tennis stroke looks like from the ground up
Acceptable vs. problematic asymmetries — identifying which imbalances quietly degrade shot quality over a long season
These are no longer hypothetical questions. They're the next frontier — and the foundation is already in place.
Joey Kalbas is Director of Data Analytics for a top-10 nationally ranked Division I tennis program.
