Berger was a massive pain in the arse, after he left Benetton I read an article about him in F1 magazine written by an one of Berger's engineers, he said Berger complained about anything and everything and was never satisfied, he stated that he and several engineers spent an entire day of testing just trying to get the throttle pedal the right shape they had to make and adjust about 10 of them before Berger finally decided he liked the one he had on at the beginning of the session.RasputinLives
What did Berger bring to Benetton over Herbert apart from costing more money to hire in the first place like Alan Jones said one weekend Berger challenges for race win and another weekend he's way down in 15th or something
He said nobody liked working with him and they would waste hours just fiddling with the tiniest most insignificant part of the car rather than getting the setup right...
Which probably explains why his results were so erratic....