Despite sitting second in the standings, Vinales has endured a low-key start to the season as he only has one top-four result to his name, and is 36 points behind Marc Marquez.

In the meantime, satellite Yamaha rider Zarco - who rides a 2016-specification YZR-M1 - was in podium contention on four occasions in five races, and has finished second twice.

Zarco has also been stronger over one lap, securing pole position in Qatar and Le Mans respectively and placing no lower than fourth in any qualifying in 2018 so far.

Vinales says that the fact Zarco has been able to be competitive on a Yamaha is proof that the factory outfit has made a mistake in the past.

"The bike is going well, you just have to look at Zarco," said Vinales at Le Mans.

"It is a point of reference for me, and proof that Yamaha was wrong at one point.

"We were simply wrong at some point. Surely in the pre-season I didn't follow the path I should have."

15 races without win "no coincidence" - Rossi

The French Grand Prix was the 15th MotoGP race in a row where Yamaha has failed to win, and Rossi reckons such a long streak is "not a coincidence".

Rossi said Yamaha's current performance is "not enough" if it wants to go back to winning ways, and urged his team to work on the issues faster as it is usually "not very reactive".

"I think it's not a coincidence. If we want to win, this is not enough," said Rossi.

"I like working with them [Yamaha] but now we need to react quickly. Historically, Yamaha is not very reactive.

"Now it is very important to stay focused and hope that in the second part of the season we will be able to improve the bike.

"If we can't get podiums, we must at least try to stay in the top five to score as many points as possible."

Additional reporting by Jamie Klein