Retirement, why?
We know from during Gus's tenure that he had an injury that had to be managed and was proving difficult to resolve. Hence his regular spells of being injured.
This time though he has come back and seems unable or unwilling to sprint. That for me is a major worry as before a player comes back on the pitch he should have been brought up to full sprinting capability in training. Either his physical condition has deteriorated so that he can't sprint to anywhere near the same speed as before or he is scared to, in case he injures himself.
This problem has been hanging over him for some years now. Take the speed out of Will Buckley's game and what have you got left.
I wonder whether it will end his career.