I am a great supporter of Pakistani cricket team and writing this post as positive critism as everthing in the universe has room for improvement and so does our great team.
I think there are a couple of causes behind Pakistan's inability to perform well under presure (our greatest weakness). First, lack of education. Quite sadly almost all of our current players are merely high schoolers (or school drop outs) which tends our players of lacking mental development and logic building process that actually leads to correct and timely decision making ability, not to mention poor english language skills that are an embarrasment for the captain himself.
Physical ability and atheletism of every top team is perhaps almost as at the same level, but yes, Pakistan does have a chronic problem of finding consistent if not agressive openers. This lack of confidence can be over come by concentrating on the game and responsibility on the shoulders rathen than a mere offort of showing fancy style.
lastly, I would say management hasnt been to its best for the last few years. Our current PCB boss has no idea what cricket is all about and the previous bosses have ruined our great talent. Had Afridi been a part of Australian team, they would've extracted the very best out of him, but we simply wasted all his talents by blindly sending him as opener for years but not training him as how to become a good opener. All we thought was we needed a slugger to hit over the 30 yard circle in the first 15 overs. What a wrecked thought.

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Had cricket been a religion, Imran Khan would've been the god.