Del Potro's defeat against Chardy must show he's not one of the 4/5 favorites, in any Grand Slam. He's like Tsonga, Berdych and Ferrer (except 2012), he can lost early in any GS.
I repeat : Del Potro is not better than Tsonga, Berdych and Ferrer, this is truth. Del Potro has not reach a semi-final in a Grand Slam since 2009 US Open !
What an ability you have to extrapolate future results from one match