Dec.21 (GMM) Lotus' need for "continuity" helped Romain Grosjean keep his job after the Frenchman's tumultuous return to Formula One in 2012.
Asked by Switzerland's Speed Week why Geneva-born Grosjean ultimately got the nod, Frenchman Boullier answered: "Continuity is a significant factor in a racing team.
"Driver changes bring unrest.
"It takes time and energy to fuse the working methods of drivers and teams," he said.
As for why Grosjean, who for the second year in succession will be Kimi Raikkonen's Lotus teammate, is the right man for the job, Boullier stated: "Cohesion, courage, speed, freshness.
"And if he develops properly, he can be made not only a Grand Prix winner, but also a world champion.
"If he develops the way we want, then soon he will be one of the top five Formula One drivers."
Grosjean made many mistakes in 2012, including the Spa start-line crash that saw him serve an ultra-rare FIA race ban at Monza.
"World champions make mistakes," Boullier acknowledged, "even if that happens rarely. I just want Romain to be competitive from the first race of the season."