My take on our defending deeper as the matches go on is of an attitudinal one - players are aware of the consequences of conceding late - they have done already this season and last, so to rectify it, try and play a more positional role in defending than a proactively "seek and destroy" type of game. Add into it the odd booking here and there and the issue of attitude is further highlighted. It's natural for more caution to creep in as time goes on, but we're almost seeing a fight or flight reaction late on in matches.