There are some of us who believe losing that weight actually hurt his effectiveness in the middle. He wasn't able to push back on centers nearly as well this season as in the past.
I'm not smart enough to predict what kind of defense DeRuyter will implement at Oregon. But given his track record, it's pretty safe to say he'll design one that fits what we have...right now the strength and potential is at linebacker so perhaps 3-4? After his past success with linebackers I'm sure Sewell, Flowe, etc. are very excited for next season.