The truth is that it has nothing to do with morale, condition, and certainly not win bonus or training bonus. The game engine creates these scenarios sometimes and expects you to react to it. If you do what the engine expects you to, then you can turn it around. Most times adjusting the position of your defenders will do the trick or a change in your orders might work, but just keep changing stuff and keep an eye out for for key stats shots on target and no of saves, if it improves in your favor then stick with that setting.

Most times I'm able to identify this kind of scenario even before I concede the first goal by watching the ratings of my defenders and also paying close attention to the number of shots on target against me and how many of those shots forced my goalie to make a save. If ten minutes into the match I see the opponent has 6 shots with 5 on target and I have 5 with 0 on target then I know I need to change something because if I don't I'll concede a lot of goals with that setting. Take this from someone who has only lost twice in the past 4 seasons.