Shehzad came in to the international scene with potential and a flaring style of batting. It was under Misbah he regressed really badly as his attitude changed and his passion took a hit. He wasn't aggressive anymore and he became boring to watch. If he wasn't Pakistani, he might have not had to play under Misbah and if given the chances if brought to the international team, he may have not regressed like he did.
The way you play has a lot to do with the leadership you play under. I am a huge Misbah fan and I respect him a lot; but it's clear the style of the team and many individuals changed under Misbah and we became a defensive team. Our slow batting is notorious around the world because of this reason. It was under Misbah that the world modernized in batting and we got left behind.
And Shehzad is one of the players that became a Misbah and with his selfish opening batting and wasting the opening powerplay, Pakistan fell behind other teams and is now suffering the aftermath. If you don't start something well, it's tough to transition into something well.