I'm not sure it did tbh. Normally ACL injuries can hamper speed and agility, but I'm not convinced this was the case with Okore. For me he has a case of Richardsitis, whereby he somehow thinks it's a good idea to regularly vacate his CB position to try and win the ball higher up the pitch. He succeeds a lot of the time, but unfortunately this is massively outweighed by the times when he fails to win the ball and our backline is totally exposed.
What made the 2nd half vs Luton so septic was the fact that we had 2 maniacs at CB vacating the position, with only a bumbling Alan Hutton to cover!