Helmut Marko has attributed McLaren's impressive improvements to the Woking-based squad "copying better" than Red Bull's other Formula 1 rivals.
McLaren have emerged from the pack in recent weeks to take the fight to the defending champions. Having started the season a cut above the rest again, Red Bull seem to have a bona fide challenger again.
Lando Norris won in Miami earlier this month and pushed Max Verstappen all the way at Imola. In Monaco last weekend, both McLaren cars finished about the two Red Bulls as Ferrari also showed they are capable of winning again.
Speaking to Austrian publication OE24, Red Bull adviser Marko explained his theory behind why this has happened. And he pointed to the fact former chief designer Rob Marshall has been engineering and design technical director at McLaren for several months now as a major reason for their improvement.
Marko said: "We are now in our third year with the current regulations, and people copy. Some copy better, and you can see the result now at McLaren. Ferrari has also constantly developed further. [After Marshall's move] the first fruits are there."
Inside the driver call which upset Red Bull and changed the course of F1 historyThe Austrian also pointed to the fact Red Bull struggled with their car throughout the Monaco weekend, adding: "Our two drivers came to Monte Carlo enthusiastically and said that the car handled the kerbs really well. But as soon as they were in the car, they said: undrivable!"
Marko hinted at what he also wrote in his Speedweek column about there being a lack of correlation between what Red Bull's simulations told them compared to what they actually experienced on the streets of Monte Carlo.
The 81-year-old wrote: "The problem starts in the simulator, which signaled that the car was going over the curbs perfectly. Simply put, that means that the simulator and reality don't correlate. And Monaco wasn't the first race track where we had this problem - the first time that it was relatively severe [was] in Singapore [last year].
"The simulator spat out something that didn't correspond to reality. That's the first point we'll address. We are optimistic that we can at least find out why the simulator produces data that does not correspond to reality. But Montreal could also be a difficult weekend for us."
Driver Verstappen is also worried about what the Canadian Grand Prix will bring for his team. The Dutchman said: "We have to wait and see. New surface as well, I think that might always give you some surprises. But it's probably also not going to be our strongest weekend because of that. But probably a little bit better than here."