From a Yahoo article:
"Harris started in the Bears’ 24-18 victory over Tampa Bay in London on Sunday with Major Wright(notes) nursing a hip injury. He had been benched for the Bears’ win over Minnesota the previous week.
That led to him requesting to be dealt, something that did not happen before the trade deadline. Harris had missed three games with a hamstring injury and struggled in a Monday night loss to Detroit before that Vikings game.
Harris was in his second stint with the Bears after being traded back from Carolina last year."
IDK, sounds like kind of a punk move to request a trade when you've been hurt and struggling all year...