When Wisconsin was part of my territory, I would avoid eating anywhere in Oshkosh. Never could find a great meal. Go to Salty's in Fond du Lac for great seafood. There is an upscale Italian restaurant on Main St in Appleton - I can't remember the name, but people up there can lead you to it. There is a steak house about 15 miles WNW of Oshkosh - hidden out in the country. I can't remember the name of it but any bartender can tell you how to get there. Just a great place and a great meal.
Wonder if you are talking about that little joint in Greenville, I have had some good meals there, cannot remember the name.
That said, I have been to Fratellos 3 - 4 times, can't say I was ever disappointed. And we enjoy their little thin crust pizza.
Oshkosh also has the granary, south side of downtown, had a couple good lunches there. It is an old grain building converted to a restaurant.