Fluke? Maybe. Trend? Maybe. Were the subsequent injuries further deterioration of the original injury? Or new injuries? I don't know the answer.

Regardless, I prefer to see how he does on the field rather than write him off based on what happened to him as long as four years ago. Many players have played at a high level after serious injuries. If he is a sitting duck back there because of poor o-line play or receivers not getting open, chances are he will get hurt (as virtually any QB might). If he is able to avoid taking many extra shots because of good o-line play and/or a quick-release passing attack, I can easily see him playing a full season (and beyond).