samir! you should know that openers have to bear the brunt of high level of energies of guys like Shoaib and Brett lee. Its very difficult to be an opener in fron of the fresh legs of such bowlers. By the time its 20-25 overs the second line bowlers come to play and in the slog overs there is no pressure of being out as its expected and by the the fast bowler are tired and most of them lose the bite.