Quite true. The issue is, how each of them deals with it.
To win a Slam you need to play and win seven matches in a fortnight. The best players have the ability to do that and manage to triumph even on the occasional off day that they all suffer. That is, they can play badly but still scrape a win. Murray does not. He achieves a couple of good victories and then loses to a relatively unknown player because he had an off day.
Even Murray himself is now doubting that he will win a Slam. I identified him about three or four years ago as what my mother would call a “sickly child”. He is prone to minor ailments which give him “off days” and he does not seem able to work through them. Further, he cannot, it seems, go a fortnight without suffering from one of those afflictions.
I have a sizeable wager with one of my pals, placed two years ago, that he will not win a Slam event before the Olympics start in 2012. (In fact, I believe he will never win one, but we had to make a cut off point for the sake of the wager).
He has seven more chances, but I think my money is safe.