The scheme is fairly straight forward - once you fail to win elections outright (which Imran Khan failed in 2013 Pakistani elections) claim that it was fraud, argue that ruling government has no legitimacy, then bring frenzied crowds on streets (how hard it is to exhort few thousands on streets?) and essentially bring riots to de-legitimize duly elected government.
One cannot compare this with Arab Spring. At least folks there were revolting against dictators. Here in Pakistan Imran Khan is railing against an elected government. In Ukraine, folks revolted against Russian Imperialism and after that they did elect the President by an outright majority. In Egypt, Army eventually moved against incompetent government of Muslim Brotherhood Morsi; though it was democratically elected.
What is not clear is whether one can blame Nawaz Sharif government for all that ails in Pakistan. In that sense Imran's charge that it is all Sharif government's problem is hard to accept. It is so because, it is guaranteed that tomorrow even if Imran Khan becomes Pakistani Prime Minister (not that another opposition figure Quadri will easily back him); Pakistan's problems will not be solved.
One has to understand, no government can run when only 1% or so people are paying tax while rest of the Pakistan simply pilling on freebies. On top of it Imran Khan is exhorting Pakistan to stop paying taxes and utility bills! Pakistan is ruled by a feudal system where huge land holding landlords and their crony business partners are controlling all of Pakistani Economy. Pakistan does not have any cushion like Saudi Ghawar Oil Field nor North Field Gas like Qatar to roll out 'totally on government tab' lifestyle to most in the society. Imran Khan himself is the poster child of such a feudal mentality. Never proven in the field of business nor has led any constructive political movement; he behaves as someone who cannot overcome the lust of 'power'. He is the prominent 'mud thrower, rabble rouser' of Pakistan. Sure Nawaz Sharif is a land lord too, but at least he has ran a successful business empire providing jobs to many Pakistanis. Apart from defeating India and England on their home grounds to win Cricket Test Match Series first time for Pakistan in 1987 and then lifting World Cup in 1992, Imran Khan does not have any worthwhile achievements under his belt which can help common Pakistanis. He was responsible for killing of innocent Pakistanis just because allegedly someone flushed Kuran in a toilet and otherwise is essentially a 'play boy Pathan' charming ladies all over the world.
One suspects that as PM Nawaz Sharif entertains a sensible policy of peace with India and against Talibans in Pakistan; many powerful Pakistanis would see that as an attempt to correct the fundamental 'imbalance of Pakistani State': substantial resources going to Army instead of development for common and poor Pakistanis. And that is the danger that disgruntled Army may side with Imran Khan. Clearly Imran Khan is aiming for such an implicit backing and that is why he is playing increasingly with fire. Hardly any of these developments are helpful for Pakistan.