The forward, who also managed the Blues, was sacked by Stamford Bridge in 1998. Now, 27 years later and nearly 20 full-time managers on.
According to him, some of the issues with the Londoners still persist, as he questions their identity, philosophy, and tendency to frequently sack managers.
"Chelsea to me, still, is a little bit of an enigma. I don't know really how good they are or how bad they are. They are looking for their identity a little bit,” Gullit wrote in the Sun.
"They are trying to creep up the table and maybe in the long term they will be contenders for the title. But I don't know yet where they are exactly.
"People tell me that one of the problems with Chelsea is that they change the manager all the time - so tell me something new! I don't get it. I don't get what they really, really want.
"Even if they are successful, they still sack you as a coach. So I don't know. That's why I say Chelsea's still an enigma.
"I try to find out what they stand for, what is their philosophy and what is the football they want us to watch?"