Shahid Yousuf called in from the A team

I don't get this. Nothing against Shahid Yousuf, but why is an A team bat being called in, while Asim Kamal, Bazid Khan, Yasir Hamed and Faisal Iqbal are under contract, and not being asked to play. Shahid Yousuf has had a few very strong performances for the A squad, and probably deserves a call up, but what about everyone else?