Simply put if you’re not filling your mind with positive thoughts, negative ones will override. A person who’s fired might be thinking negatively and hence his/her career performance declines. Accordingly he is picked for the layoff.

It could also be true that this person didn’t picture himself getting laid off BUT pictured himself getting misery! People feel sorry for him, etc. the LOA can manifest according to one’s feelings not necessarily the exact action (ie layoff).