What exactly happened as Pakistan drop seven players, sack coach in between England Test series?

After a 194-run defeat to England at Headingley, Pakistan have made an extraordinary mid-series overhaul. They have released seven players from the squad and also removed head coach Sarfaraz Ahmed and bowling coach Umar Gul. Interestingly, five uncapped players have been called up, while Saim Ayub and Abdullah Fazal have also found a place. However, collectively, they have only 10 Test appearances between them.