Obviously disappointing for Fabbri. Big fan of his, despite not being a Blues fan. I am confident he can return to being a solid player and contribute.
I tore my ACL revision at about the same time frame after surgery that Fabbri did, although playing soccer rather than hockey. Went through a similar process where it swelled up, and I didn't realize I tore until much later. I also proceeded to live and play beer league soccer without an ACL for 5 years which was entirely stupid, but not relevant. Looking back, I could have been rehabbed better. I was also cleared by my surgeon to start playing again, passing all his tests. At the time, it felt great but in retrospect I needed to get stronger, much stronger. I could speculate something similar where he felt ready, passed all tests, but you don't really know what ready is, until it is too late. I am currently going through the recovery (2 months out) on the second surgery now. All is going quite well, ahead of schedule actually, but I've learned a lot about what the meaning of knee stability/muscle requirements really are. Ultimately, persistent patience and a lot of hard work is critical. It's something that is rehabbed in PT and the gym for a long time, and you can start to feel back to normal even when you are not quite there. I didn't grasp that concept going through it the first time. Regardless, if Fabbri takes his time he'll get back to 100% or near 100%.
Also, side note the 3% sounds conservative. ACL grafts fail frequently although the numbers have dropped dramatically lately.