The major problem for Pakistani economy is corruption, in case Marshall there is smaller cabinate, less people to rule. Also mainly under military dictatorship there is unity in federation because singularity of rule and no democrasy.
Other factors also play the role are like controlled economy stats get released by government. Military rules show better results since there is no musical chair, noora kushti government come into play, that is the reason before military go, economy stats generally go down. It happened in ayub khan and Musharaf ending terms. But Zia rule didnt see much criples economy wise since he was never planning to leave the chair.
That is the reason military rule shows better results as compare to Democrasy atleast for Pakistan.
Pakistan seriously should look for alernative to democrasy. may be security country. This shitty democrasy also divides country men into many groups.
PS: musharaf avg was around 5%-6%, only two years 2003-2004 it touched to 6.5%, but mainly it was less then 6%.