Maybe it is possible he didn't let the trainers know he had an injury initially and he maybe did further damage to his ligament that now will need a longer rehab and we don't know when the zone he's learning makes it into his skillset as needed fir the defense we are running.
Initially got in mcds doghouse for not playing as well as they knew he could, then once the injury was identified they started proper treatment. Did he require surgery? We don't know unless and until Elam himself decides to share such medical info.