Former McLaren team manager Jo Ramirez believes Sergio Perez's "very bad" attitude is what cost him his McLaren race-seat.
Perez joined McLaren in 2013 on the back of a stellar season with Sauber. However, his days in Woking were cut short when, after just one season, the team dropped him in favour of Kevin Magnussen.
And although fellow Mexican Ramirez feels Perez had the pace to last at McLaren, he says it was his poor attitude that ultimately cost him.
"As a driver Sergio was actually not bad and I thought he was also getting better but McLaren wanted a new Lewis Hamilton, they wanted a driver who is faster than Jenson Button," Ramirez said in an interview with motorline.cc.
"Sergio was not good enough as a person.
"He did not really cooperate with the team, he was at no time a part of the team, he was cocky. 'I am now a Formula 1 driver' - we know the drill.
"His attitude was very bad. He was unpopular with the engineers, with everyone in the team - he was regarded as very arrogant.
"And Ron Dennis requires that his drivers are part of the team. From early in the morning until late at night you must always think of McLaren."
As for Esteban Gutierrez, Ramirez says while he is "not a bad driver", the Sauber youngster has a "lack of killer instinct."