I think this is what Mixum is saying (I've been hired as his spokesman). Batum had a little pain on and off over the months, causing him to usually tough it out, but sometimes to have to refrain from playing. The pain got more consistent during the preseason, causing the surgery.
Now, should the doctors or Pritchard have foreseen this need for surgery, and gotten it done earlier so as to minimize the impact on the season? Well, not being a doctor, I don't know the tests that would have predicted whether this thing would get worse, as it did. And I don't know whether it is customary to take preventive action or exploratory surgery, to find out.
Now that I typed out the logic here, I can see you need medical knowledge to take the logic any further, which I doubt Mixum has.