Build or Buy: Should You Build Your Own Performance Tool?
AI coding agents made building cheap. Before building a performance tool, audit what your platform already does, who maintains the result, and which part is genuinely missing.
Read the essay MD · MS · RSCC — Sports Science & Performance
Human performance,
Human performance,
read like a physician.
I’m Mauro Castillo. Physician, sports scientist, and strength & conditioning coach. I’ve trained pro athletes in baseball and basketball, and I build the AI systems that run fitness businesses.
Experience
From the notebookIdeas for the
Ideas for the
next session.
Field notes on sports science, coaching, and building with AI.
Browse all writingAthlete Monitoring: How to Turn Data Into Useful Decisions
Give athlete-monitoring data a clear purpose. Define each metric, separate observations from interpretations, and assign a responsible person to every flag.
Read the essayAthlete Profiles: How to Interpret AI Scores and Coaching Preferences
Use athlete profiles with context. Learn what AI talent scores, wearable data, and coaching preferences can—and cannot—tell performance staff.
Read the essay The lens Three disciplines,
Three disciplines,
one way of seeing the body.
MD
Medical Doctor
Physiology and the human body, understood at a clinical level of detail.
MS
Master of Science
Trained to read the evidence and design method that holds up.
RSCC
Registered Strength and Conditioning Coach
NSCA designation recognizing experience and knowledge in team strength and conditioning.
Capabilities One person,
One person,
four toolboxes.
Most staffs split these across four hires. I work across all of them, and they sharpen each other.
Clinical The MD lens on every training decision.
Clinical & Medical
- Physiology and pathophysiology at a clinical level
- Injury context, red flags, and return-to-play thinking
- Reading, appraising, and applying the research
S&C On-floor coaching in pro environments.
Strength & Conditioning
- Program design and periodization for team-sport athletes
- Day-to-day coaching in pro baseball and basketball settings
- Testing, monitoring, and load management that coaches actually use
Sport Sci From raw signal to a decision.
Sports Science & Data
- Force plates, GPS, and velocity: VALD, Catapult, Kinexon, 1080 Motion
- AMS platforms (Teamworks) as the daily operating layer
- Turning monitoring data into answers a coach can act on
AI I don’t just use the tools. I build them.
AI & Software
- LLM agent systems designed and shipped end to end
- Agentic coding with Anthropic Claude Code and OpenAI Codex
- Automation pipelines that glue a team’s stack together (n8n)
Tools I work with
VALDCatapult1080 MotionTeamworksKinexonAMS platformsAnthropic Claude CodeOpenAI Codexn8nLLM AgentsRailwayVercel
Selected work A sample of what
See all work
A sample of what
I’ve built and written.
Strength & Conditioning Coach MiLB
Texas Rangers
S&C coach in the Rangers' minor-league system. Named 2025 Carolina League Strength & Conditioning Coach of the Year.
S&C & Sports Science Fellow NBA G League
Texas Legends
Fellowship in strength & conditioning and sports science with the Dallas Mavericks' NBA G League affiliate.
Athlete Development Baseball
Cressey Sports Performance
Athlete development at one of baseball's most respected performance facilities.
About
I’m a physician who coaches. I hold an MD and a master’s in science, and I’m an NSCA Registered Strength and Conditioning Coach (RSCC). I bring all three perspectives onto the field.
On the performance side: strength & conditioning coach in the Texas Rangers organization, where I was named 2025 Carolina League Strength & Conditioning Coach of the Year. A fellowship in strength & conditioning and sports science with the Texas Legends, the Dallas Mavericks’ G League affiliate. Athlete development at Cressey Sports Performance.
On the systems side: I wrote Prompting for Performance, the AI playbook for S&C coaches, and I build AI software for the fitness industry. I don’t just specify systems, I design and ship them.
Dominican-born, based in Jupiter, Florida. This is where I keep the work I’m proud of and the ideas I’m still testing.