Not sure claiming it takes 2 years to come back from ACL is accurate barring if further complications in the come back.
From top of head - Xavi was back playing at top top level when came back, Roy Keane came back and inspired Man Utd to the treble as their player of year, Wirtz has come back from ACL and looked top class very quickly etc.
Those are just example that come to mind of midfielders but cant see anywhere that clubs would expect it to take 2 years.
Also treatment come on since days of Xavi and Keane.
Cant argue one moment that Gavi looks like never been away then as soon as not as good as some make out that he is still recovering from ACL.
Most of what he lacks/good at is same as before just a bit worse.
He has for last few seasons been poorer than majority other midfielders for chances created, breaking lines, goals/assists, pass %, progressive carries etc, always been relatively slow and not the most mobile, poor positionally.
This season so far he has been worse but lets no pretned he was ever elite in a lot of those areas he is badly lacking in at again.