Daniel Ricciardo says his poor second half of 2018 has been "complex and confusing".
The Australian had a strong beginning to the season, even winning in China and Monaco. But since his 2019 switch to Renault was announced, Ricciardo has struggled.
"I don't remember a black cat crossing my path," Ricciardo, who reportedly punched a hole in his driver room wall a week ago in Austin, said in Mexico.
"I really don't understand what is happening but I don't have the feeling that I need to change my approach.
"At the beginning of the season I was very strong but I personally didn't change anything after Monaco.
"I've tried to understand it and become better, but it's strange that the season was divided into two parts for me. It's quite incredible actually and I don't understand how it is possible," he added.
