The standard of whether a surgery is essential or not is being left open to the interpretation of the doctor performing the surgery. That being the case, a doctor can pretty much interpret that standard to fit his and his patient's agenda.
Here is the standard outlined in Florida's ban on non-essential surgeries:
“medically unnecessary, non-urgent or non-emergency procedure or surgery which, if delayed, does not place a patient’s immediate health, safety, or well-being at risk, or will, if delayed, not contribute to the worsening of a serious or life-threatening medical condition,” that standard is being left to the interpretation of doctors."
I don't see how TJS for pitchers fits that standard. Even if the condition might worsen, which I really doubt would happen if the pitchers followed the resting guidelines of their doctors, it is not worsening to a point of being a "serious or life-threatening medical condition".
Orthopedic doctors that were questioned who are not directly vested in these cases say that TJS is absolutely elective.