Pitching velocity development - what actually works?

At that age, focus on mechanics and arm care first. Velocity will come with physical maturity. Driveline is good but expensive.

Long toss program and proper strength training. 78-80 at 16 is solid - he'll likely gain naturally through senior year.

I went from 82 to 88 between junior and senior year. Lots of long toss, weighted balls, and lifting. Be patient!