Every job has a profile. If you are dealing with the public and the media, it is important to have good communication skills. Many folks fail job interviews with 4.0 GPAs and stellar academic records because they were not able to make a good impression and were unable to communicate effectively, even though are not going to interact with people on daily basis.
Similarly, a cricket captain needs to a good communicator, and English has become a requirement because only English speaking countries (and countries with English as an official language) play the game, unlike football or tennis. You don't have any French or Spanish journalists asking questions, but you have English speaking journalists and if there is a considerable language-barrier, then it becomes a problem.
For some reason, this topic hits a lot of nerves and triggers folks easily. I am not criticizing Sarfraz because he comes from a humble background and did not have the exposure (and he is actually improving), but the fact is that having a captain who can express himself fluently and coherently is a major plus point. Just look at the way the likes of Kohli and Mathews carry themselves in press conferences and communicate with the journalists and then compare him to Sarfraz, who is a nervous talker in both English and Urdu, seems to be a little camera shy and is not coherent at all. His press-conferences are a complete mess because he is all over the place with his statements.
Obviously, good communication skills cannot take precedence over cricket skills. Masood is the best speaker in the team, but he is a rubbish player. However, having quality players who are also good speakers is a big advantage, and this why the PCB needs to step in - and not listen to the people in this thread - and provide media training to domestic players so that they are not deer in headlights when they have to confront the media.
It seems like people here enjoy the embarrassment the likes of Umar had to face during the 2014 WT20, when he talked about North when asked about South, because who cares about English etc., we are proud Pakistanis and should only communicate in Urdu and let's get over the "colonial mindset" bla bla.
As captain of Pakistan, Sarfraz has to improve his communication skills. In cricketing terms, it means improving his English and his overall coherence (which is found wanting in Urdu as well). That's all.