Inter Milan president Massimo Moratti was furious after defeat to AC Milan on Sunday.
Inter offered a limp display for the 1-0 loss.
"It doesn't seem to me like we suffered against Milan's play," Moratti said. "The problem is that we actually didn't play. It's a different thing entirely and much more grave.
"I didn't like anything. One can understand losing a derby, but this time I didn't like the approach or the aftermath.
"We didn't do enough to think about winning. This won't do at all. It was an ugly game and we did nothing because we became different."