While the team have not scored points in the opening four races of their renewed partnership with Honda, Boullier says changes away from the circuit are having a marked impact – particularly with regards to updates, which proved hit and miss in 2014.
"There's been a huge change in overall culture and philosophy. At every level of the company, there is clear leadership," Boullier explained.
"We agree the direction we want to pursue, and we bring people with us. The attitude has changed from 'telling' people, to 'asking' people; we've integrated people, and we share opinions and ideas.
"The main outcome of that new approach is that people now have a sense of ownership in the car. To give you an example, I guess about 50 per cent of the upgrades we brought to the track last year didn't completely work; this year, we've brought that down to about five or 10 per cent.
"There's tangible change at the factory, too: we've been able to increase our in-house manufacturing capability by around 30 per cent - which makes our development cycle lighter, faster and more flexible."
Chief engineer Peter Prodromou, who has steered McLaren's aerodynamic philosophy since being recruited from Red Bull, said that McLaren will continue to develop the MP4-30 until the final race of the year, in part to help them hit the ground running next season.
"Over the last couple of seasons, the team slightly lost its way aerodynamically," he said. "It became obvious that if we'd carried on with the previous concept, there'd only be so much we could achieve.
"So we've begun to establish a new aerodynamic concept, and a different way of working, too. That new concept has majorly shaped where the team's heading in the future.
"Next year's car will be an evolution of this year's, so we need to keep developing it right until the final race."
Speaking after this year's Grand Prix in Bahrain, Fernando Alonso predicted that McLaren will make a "huge step" forward at his home race in Barcelona.