The deal caught Lotus by surprise.
"We knew he would be good, and we knew we would be good, but we didn't know it would be that good!" team owner Gerard Lopez smiled recently.
Now, after Raikkonen said he is leaving for Ferrari next year only because his pay is late, the 33-year-old's dream pairing with Lotus is ending somewhat sourly.
Asked by Speed Week to say what the 2007 world champion brought to the team, boss Boullier answered: "That is difficult to define.
"Without us, Kimi's return to F1 would have been a different picture," he said.
"Can you imagine how it would have been if he had signed for Williams and not us? We built everything around Kimi.
"I think as a Lotus driver he became even more interesting to the fans. He gained in popularity," said the Frenchman.
"If he had retired after his rally phase, I think Kimi Raikkonen would be forgotten today," added Boullier.
"We gave him the right tools to get his self-confidence back."
Told of the rumour that Raikkonen is the highest paid driver in 2013, Boullier smiled before answering: "That is quite likely."
So now, with Raikkonen departing, Boullier confirmed that Romain Grosjean is staying at Lotus in 2014.
And with Nico Hulkenberg and Felipe Massa the front-runners to replace Raikkonen, Boullier said he is looking for "Someone who is uncomfortable for Romain".
"I don't want him to be in a cocoon of well-being."