It's a tough one as there is a push for not performing surgery for ACL 'injuries'. Sometimes there are differing opinions on MRIs as to whether there is a full rupture or not, and if not whether it can recover on its own. The ACL is not in an area of the knee that gets good blood flow as it's internal compared to say the MCL which is on the outer of the knee and gets greater flow and is easier to see the condition in scans. From what I've read there were conflicting opinions with his original injury as to whether surgery was required. If it was a full rupture then surgery is definitely required as you need your ACL to play any level of sport let alone professionally. The ACL (in the middle of the knee) and the PCL (at the back) are the cruciate ligaments that form a cross to prevent the knee from being able to twist the wrong way (hence the name cruciate). After choosing the non-surgical option they must have done further MRIs that showed that the ligament was connected and presumably had increased in size/condition. Subsequent to returning he's injured it again, this time regardless of whether it's a complete rupture or not they'll have to go with surgery. Thing is there are many options for the surgery itself, each with pros and cons. Generally the best option for long term outcome is a graft using either hamstring or patella with a very slight reduction in recurrence percentage when using patella. Other options can be to use a donor (cadaver), but there is a higher chance or recurrence, though the benefit is there's no need for rehabilitation of the hamstring/patella. In my case I used my own hamstring, and subsequently suffered multiple hamstring injuries during my recovery from doing relatively mundane tasks. Hamstring seems to be mostly ok now which has helped to get the knee recovery back on track. There's also loads of different conjecture around the best angles for the graft to be attached, it's complicated stuff and having gone through some of it you can understand how his situation has played out like it did. Hindsight is always 20/20 but of course now we know they should have opted for surgery originally. He'd have missed the rest of this season as a minimum but given how he's not been himself simce returning that wouldn't have been such an issue anyway.