Ciro Ferrara has attacked former club Sampdoria.
Ferrara was sacked after a seventh consecutive defeat on December 17.
"After I was fired, it was only right to keep my silence until the club secured mathematical safety," said the former Juventus and Italy Under-21 tactician.
"I picked up 18 points in 17 games. In his first 17 matches in charge, Rossi only earned one more point. I have nothing against Delio, a professional who I respect, but the results we achieved are pretty much identical.
"Some people have analysed the statistics in a skewed manner and I'd recommend they go back to a basic mathematics class."