I find this section from Chris Brown's article today interesting:
To me, that says the Bills recommended to Crowell that he have surgery 3 weeks ago and he said no and instead tried to do non-surgical things to help his knee get better. Apparently that didn't work and he couldn't take the pain any longer so he decided to have surgery. I don't think it was malicious on either side's part, although I think the Bills were frustrated that they could have had an answer (on recovery) 3 weeks ago and been better able to plan for his absence.
He might as well have the surgery now that the die has been cast. Playing on a bad knee in a new system (assuming the Bills reach an injury settlement with him) won't get him very far. And reportedly if a settlement is worked-out in the next 4 days, the Bills can re-sign him at a later (which I don't know) date. Ideally at that time he'd be healthy and he knows the system, can show his stuff, and cash-in next year.