Yeah devastating might be too harsh a description when the great advances in knee surgery are considered, though his injury also included a torn MCL too...I don't think ACLs are "devastating" injuries anymore with today's medical advances. Its obviously a serious injury when its sustained and derails your season, but they don't really ever have any long term detriments from that type of injury anymore.. pretty cookie cutter procedure and rehab process that leads to a full recovery
Adrain Peterson (granted a freak outlier) came back from his ACL surgery after like 8 months and nearly won the league MVP that year, rushing for over 2000 yards
I don't expect an AP-like recovery from Miller, but then again I'm not sure what to expect from him, for two basic reasons:
1) He's never suffered an injury like this one before, to his credit, so his rate of recovery from it is an unknown factor; and
2) because of limited off-season player/free agent access this year, is the team taking a somewhat bigger leap of faith more than it usually might vs making a more thorough medical evaluation?
One more thought: Miller has logged almost 1400 regular- & post-season carries in his NFL career, so the tread on his tires need to be closely monitored...