Dislocated knee / structural damage means more ligaments involved. Was any cartilage and / or Patella tendon involved as well? If a RB or WR, might not be back at beginning of 2017. As a QB, might be back in time.
Bigger, stronger, faster players. Get spikes stuck in ground; player gets off balance... freakish injuries.
To quote researchers quoted in the Journal of Athletic Training-
" Noncontact ACL injuries are likely to happen during deceleration and acceleration motions with excessive quadriceps contraction and reduced hamstrings co-contraction at or near full knee extension. "