I have been a big Dunn fan for a couple years now, I don't plan on cutting him just yet based on this performance though. Dunn works very good in the WC offense. He has outperformed my expectations of him this season, but I don't believe this game is a harbinger of things to come.
Dunn will continue to get majority of the carries. But SD has a strong line and they needed a power back (TJ) to move the line and bounce off guys rather than get tackled. I think what is getting ready to happen though is that everybody's predictions in the preseason about the RB situation is getting ready to materialize. That is that Dunn will start getting the yardage and TJ will start to get the short ydg. The only good thing about that is that when Dunn scores, he usually does it from 122+ yards out, which means TJ would not be necessary.
Dunn is getting ready to lose value. But He is still worth keeping for Bye and Injury fill-ins.