Why do you think Sher Shah is regarded the forerunner of Akbar ?

Sher Shah is regarded as the forerunner of Akbar because Sher Shah introduced many of the administrative reforms that Akbar would consolidate further. For example,

1. Akbar followed Sher Shah's practice of dividing up the empire into provinces.
2. Akbar followed Sher Shah's methods of land administration. Sher Shah started the method of dividing up the land and taxing the land according to productivity. Akbar followed this method. 
2. Sher Shah started the practice of treating his Hindu and Muslim subjects as equal, which Akbar followed.