Call me crazy, but did Detroit ever really give Harrington a group of people on the field that were worth anything?
I'm not saying he was a great QB, but if he went to the right team, with the right weapons, he could do well. Imagine if he played somewhere with an awesome defense, good recievers, and a good RB. Would he be as terrible as he was in Detroit? I think not.
Again this post reveals that the QB takes too much of the blame most of the time.