The thing about Orton is that he does nothing particularly well. Everything he does is either average(accuracy), below average(mobility), or woefully inept(clutch performance). The one thing we thought he did at close to an elite level was protect the ball, but even when it looked like that it was more about his unwillingness to take a chance which hurt us bad. This season he proved he could turn the ball over as much as anyone.
The even bigger problem and the thing that I believe puts him in the category of "needs to be replaced" is that he performs his worst when he is needed the most. We saw it for 2+ years.
I honestly consider Orton to be one of the bottom five starting QBs in the NFL.