It isn't just Rossi - Stoner, Hayden, Capirossi, Melandri, Abraham, Barbera, Barros, Elias have all had issues with the handling of the Ducati. When you have that number of riders, many of them previous world Champions, complaining about the handling and development, you have to stop drinking the Ducati Love Kool-Ade and start to think that they may have a point.
You are right though, it isn't a dog - it is a race bike that is around a second away from the fast time. The problem is, at this level, it isn't allowing ANY rider to be competitive.
Some tracks the Yamaha has the edge, some tracks the Honda, but there are no tracks where the Ducati has the edge and there hasn't been since 2010, despite Rossi's lucky two podiums.
It isn't a dog, but it isn't competitive at this high level.
Bagging Rossi for his inability to come to grips with the Ducati is to ignore the fact that no-one else has been able to come to grips with the Ducati. He isn't alone.