Getting Tommy John surgery is not like hitting a "reset" button. I tell athletes it's not like they have a brand-new engine in their arm. I just fixed the ligament. But it's up to them to fix what caused the ligament to fail in the first place. Otherwise, they're going to be what I call a two-time offender – they'll come right back for another surgery.
It's vital to temper expectations. A high school pitcher who has Tommy John surgery has a 70% chance to make it back to playing in high school – that's not college, the minors or the majors – that's the odds of playing high school baseball again.