Ranieri has returned to Roma for the third time in his career and opened up with defeat to Napoli on Sunday.
Cassano said on Viva el Futbol: "The calendar is complicated now. They have hired a coach like Ranieri, who I respect as a person, a Trapattoni-like profile that doesn't give you anything.
"They have lined up a 4-5-1 that I struggled to find the meaning of. I don't understand what message they want to give to the team. In Naples they took Pellegrini off after a half. In the post-match he said they saw positive things, just like Juric said. I don't know what they saw. Hummels never plays and in fact he struggles."
Cassano then went on to explain that he finds it difficult to understand what the Giallorossi need: "I don't know what the right medicine is for Roma, I know the place well. In 2005 we saved ourselves on the penultimate day, but we had a team with many champions.
"When you find yourself in the lower reaches of the table, the pressure increases, the city becomes a disaster, home games a nightmare. We got out of it I don't know how."