It has more to do with the respect that the players give the captain than performance IMO.Inzi had a ridiculous purple patch during his tenure,but there was also a time where Yousuf was the undisputed number one player in the team.I think it's got more to do with the father figure image of the captian.Both Imran and Inzi were the oldest players in the side,and where therefore more likely to command respect and authority than anyone else in the dressing room,thus they made good captains.The same logic can be applied to Afridi,whereas he may not be the oldest player in the team,but he is the most experienced one,and he does have the elder brother vibe about him that players like Umar Akmal,Ahmed Shahzad,Mohammad Hafeez,Umar Gul,Asad Shafique,Fawad Alam etc associate with him.Afridi is known as 'Lala' in the team,which is Pushto for 'Elder Brother'.Misbah doesn't seem to have that same thing about him.He's very calm and composed,and perhaps has a better tactical mind than Afridi as captaincy goes,but he doesn't seem to be someone that the players look upto.You could see that with Afridi where everyone would flock around him everytime he took a catch or a wicket.He had the backing of his team.I don't see Misbah having that,and even if he does,it's not as strong as the support Afridi enjoyed from his team on the field.