LONDON - McLaren has recognised that it does not know just how good rookie driver Sergio Perez really is.Perez has failed to score a point in four races since he was announced in September 2012 as a successor to departing Lewis Hamilton, who will be racing for Mercedes in 2013.Perez has chalked up three podium finishes in 2012 with Sauber.'WE DON'T KNOW'McLaren team principal Martin Whitmarsh said: "I think he's got a lot of talent but if I'm honest, I don't know."We wouldn't have signed him unless we thought that he could go to another level, but we don't know."Perez is the same age as Hamilton was when he joined McLaren in 2007. He has been at Sauber for two years and was seen initially as a "pay driver", someone who owes his seat as much to the financial backing he brings as his talent.That notion changed in 2012 with Perez earning considerable praise for the way in which he has managed tyres and fought for podium placings. Moving to McLaren, the second most successful team in Formula 1, brings far more pressure than racing for Sauber.ELEMENT OF RISKPerez will be paired with 2009 F1 world champion Jenson Button.Whitmarsh said: "There's been examples of drivers who have got a lot of talent and they can live with that pressure and deliver and others that can't."I think it would be foolish of me to sit here and say, taking a very young driver, there's not an element of risk in it. But we wouldn't have done it unless we felt there was a possibility. Time will tell," he said.When McLaren signed Perez, Whitmarsh said that he expected the former Ferrari academy driver to be competing to win the 2013 Australian season-opener.Whitmarsh said: "We undoubtedly believe we can develop him into a world champion in fairly short order." Ferrari president Luca di Montezemolo had said, when Perez was being mooted as a possible replacement for Felipe Massa in 2013, that he did not consider the Perez to be ready.Perez, 15th in the Abu Dhabi Grand Prix after collecting a stop/go penalty for causing a collision that brought out the safety car for the second time in the race, dismissed suggestions that his form had suffered because of the McLaren contract.Perez said: "It's just a coincidence. I am fully focused...it's normal that people start to make up stories that I'm not doing very well because of the McLaren deal or whatever but it's not true."