Running up the middle vs testing the edges

I have been pleased for the most part with our offense this year considering our rash on injuries and TE who DUI.

One thing I cannot understand however is Koetter's insistence to try and get around the edges in the run game. It has rarely worked this season, and not only do we not go anywhere, we tend to LOSE yards. We cannot afford to get off schedule against Seattle and end up in 3rd and longs against that secondary. I want to see us pound it up the middle and eat up clock! Go Bucs!