'Unpredictable' Perez is Red Bull's 'biggest problem' - Marko

Red Bull advisor Dr Helmut Marko believes "unpredictable" Sergio Perez could be Red Bull's undoing when it comes to the F1 constructors' title this season.

The Austrian feels that the 34-year-old is failing to put in "consistent, good performances" alongide Max Verstappen, who oftentimes finds himself as the one Red Bull fighting at the front of the field.

When assessing the Mexican's Hungarian Grand Prix weekend, Marko highlighted the fluctuating levels of performance the Milton Keynes team gets from its second driver.

"It was a typical grand prix weekend for Perez: unpredictable," the 81-year-old wrote in Speedweek.

"Checo [Sergio Perez] was very good on Friday and was just behind Max Verstappen, with the best long runs of all drivers as well. 

"Then unfortunately, a silly mistake in qualifying followed, resulting in the 16th starting position, followed by a very strong race to seventh place. 

"It goes up and down with him, nobody knows when he's going to shine or when he's going to make a mistake. He's just not putting in consistent, good performances."

Perez has struggled of late, collecting a mere 21 points from the past seven rounds - an average of three points per race weekend.

In that time, Max Verstappen has scored 129 points, which is five more than his team-mate's total for the season to date.

RacingNews365 understands the Mexican driver is now guaranteed to fall short of at least one of the performance clauses believed to be laid out in his recent Red Bull contract extension.

To Marko, with McLaren starting to score big points week-in-week-out, Red Bull's "biggest problem" is getting more production out of Perez - who could still find himself out of the RB20 as early as the summer break.

"Max [Verstappen] is still 76 points ahead in the drivers' championship, while McLaren has closed the gap to 51 points in the constructors' championship," said Marko.

"Verstappen's lead is three wins, so that is sufficient, if not reassuring. However, we need to perform consistently and be able to win on our own again. Defending the drivers' title will certainly be less difficult than defending the constructors' title.

"As McLaren continues to score points with both drivers, our biggest problem is that we have been scoring far too few points lately with [Sergio] Perez."