The former world champion has been outqualified six times in the last eight races by Romain Grosjean, and it was his team-mate who took the fight to Red Bull in the Japanese GP on Sunday.
Lotus' head of trackside operations Alan Permane reckons that the front end characteristics of the 2012 Pirelli construction used since Budapest do not suit Raikkonen's style.
"He doesn't like the front end," Permane told AUTOSPORT. "He doesn't like the turn in. It is not sharp enough for him.
"But, if you try to sharpen it up too much, you then lose the rear.
"It has just unsettled him a little bit. But he is getting to grips with it.
"There is no stopping Romain at the moment, that is for sure."
Permane believes the gap between Grosjean and Raikkonen has been exacerbated by the fact the grid is so close now, meaning small differences in qualifying can make a big difference in terms of starting positions.
"In race mode, Kimi is fine with the tyres," he said.
"He qualified 13th in Singapore and ninth in Korea and got two podiums. But that won't happen every week.
"You cannot rely on the safety car to deliver strong races from back there.
"You have to qualify better and that is what he is struggling with.
"It was better here. He was three tenths from Romain in Japan, but three tenths was five grid slots.
"It was that close. Normally that might have been two or three positions."
- Sports & Recreation
- Romain Grosjean
- Alan Permane