I'm an epidemiologist that works on exactly this field, and I can tell you right now, with full access to the data, it's still hard to get a handle on.

Having statistical skills is helpful, but statistics only gives part of the picture. Patients often have bad outcomes despite providers adhering to the best current standard of care. And that doesn't just fall out of the noise because there are persistent differences in the patient populations between providers. We have no reliable way to identify and quantify all of those confounding factors. The data and the clinical research simply doesn't exist yet.