Jenson Button believes a better understanding of the car, and not future updates, is needed from McLaren if they are going to make progress this season.
McLaren started the season with a double podium finish in Australia, but since then its performances have been less than memorable, with no points scored at the last two races in Bahrain and China.
While McLaren are confident that they will perform stronger at this weekend's Spanish Grand Prix, where they expect several upgrades to be installed on the car, Button believes they need to unlock the potential of the car that is present already.
"For us, it's not simply about bringing new parts to the circuit: it's about understanding and unlocking the car's secrets, and using that understanding to take bigger steps with performance," Button told crash.net.
"We're still at the early stages with our car, and, for us, it's less about the components that we fit to it, and more about the bigger picture - finding a useful direction, gaining trust in our measurements and pushing ahead.
"We all know that this team has the capacity to develop a car through a season, so I hope and trust that we'll start to push forwards again soon."
With that in mind, McLaren Racing Director believes they know exactly which areas of the car need to be improved.
"For us, the weekend will be about learning, and hopefully moving on from our disappointing performance in China last month," Boullier said.
"The root of our underperformance has been comprehensively analysed; we know the areas where our package falls short, and we've taken steps - both short- and long-term - to address those.
"While not all of those will be in evidence in Barcelona this weekend, they mark the start of a fresh push and spirit within the whole organisation."