Zarco, who was aggressively courted by KTM after impressing right away on the Tech 3-run satellite Yamaha following his arrival to MotoGP, has been unable to replicate his form since joining forces with the Austrian manufacturer on an initial two-year deal.

He has amassed just seven points from the first four races of 2019 and has not yet managed to gel with the RC16 bike, which has left him reliably trailing teammate Pol Espargaro.

“Johann's performance is simply unacceptable,” Pierer told Motorsport.com in an exclusive interview at Jerez. “He's having issues, but it's a psychological thing of his own.

“Recently he split with his life-long agent [Laurent Fellon], the man who placed him where he currently is.

“The people surrounding him now are creating more complications than anything else.

“At this level of competition, the last step is always psychological. Besides, he has to accept that our bike isn't a Yamaha, with its inline four cylinders [as opposed to KTM's V4 engine configuration].

“I myself will push him until he delivers at the level appropriate to our goals, that is for sure.”

After four races, KTM sits last of the six brands in the manufacturers' standings with 21 points, which is seven points more than it had at this stage in 2018.

All of its points have come from Espargaro, who has been the highest-placed of the four KTM rider in each race so far.

Pierer, who believes the RC16's gains are bigger than the results have suggested so far, has also indicated he's been buoyed by the premier class debut of Miguel Oliveira, who is riding for KTM's new satellite outfit Tech 3 and has just been handed a contract extension.

“I think our expectations in MotoGP will be accomplished in our third year, but the progress is bigger than what the points show,” he said.

“As I said, the disappointment is Zarco, he isn't up to it. On the other hand, I am very happy with Oliveira.”

Pierer has also voiced his dissatisfaction with the current state of KTM's Moto2 programme, with the Austrian bikes generally struggling in the intermediate class and yet to score a podium since the off-season switch to a new engine formula.

“I’m very mad with our Moto2 project. I mean that regarding the development of the bike,” Pierer said. “I’m not referring to our riders because we have Brad Binder, the best of the category.

“In [the next race at] Le Mans we will be able to see a step forward in terms of material.”