Edexcel History - Russian answer for your perusal - marks?Watch
In 1917, the Tsar Nicholas II and the Provisional Government - the two major governing bodies in Russia in that year - both fell. Weak leadership certainly played a role in their downfall, with the Tsar having displayed several instances of incompetence in the years prior, and the Provisional Government's infrastructure being extremely haphazard and not far-reaching, though there were arguably other, potentially more significant factors, such as the impact of WW1 and Lenin respectively.
Poor leadership definitely was integral to the downfall of the Tsar. For instance, he replaced his uncle Nikolai as one of the main leaders of the Russian army during World War One, and proved himself to be a very poor leader, ultimately contributing to the failure of the critical Brusilov Offensive, which was seen as national humiliation and thus leading to calls for the Tsar's abdication. In addition, in his absence, he made the questionable decision of leaving the Tsarina in charge, and her unpopular jurisdictions reflected poorly on the Tsar and only increased support for a revolution. Moreover, his dissolution of the State Dumas led many to believe that he was against any sort of reactionary reforms, even if they would prove beneficial for the country, and therefore could not be trusted. Indeed, even Octobrists felt he could not be given a second chance, removing the remaining sliver of support he retained from 1905. His induction of Stolypin, who used extensive terror tactics, did little to reinforce his popularity, creating a much more willing audience for his abdication and making his downfall all the more likely.
However, there were arguably other factors which contributed to Nicholas II's defeat. Although not directly invoked by the Tsar, the economic strain on the Home Front during the war threw many of his inadequacies into light and made him appear incompetent and ill-suited to run the country. Also of note was the role of Rasputin, a Siberian monk who held great influence over the Tsarina - as such, many of her poor decisions can be attributed to him, rather than the Tsar; therefore, he too was integral in bringing about the Tsar's fall. Perhaps most significantly though, the 1917 Revolution proved to be a fatal blow for the Tsar, as the armed forces defected, most notably the Pavlovsky troops who refused to fire on protesters, and as the armed forces were one of the few groups remaining loyal to him in 1905, the Tsar's downfall was all but inevitable following all this.
In terms of the Provisional Government, they were plagued with issues with leadership from the very beginning. At its inception, it had a problem with legitimacy; it was arguably 'cobbled together' hastily to replace the Tsar, mostly by liberals who were, in the grand scheme of things, a minority group. This served to undermine the Government's efforts from the start. In addition, even once instated, they had little control over the countryside, with over 700 peasant uprisings being reported, and as this was one of the crucial issues with Russia at the time - and the Government had explicitly said they would deal with it - it proved detrimental to them, in terms of both support and reputation. Perhaps most significantly, Kerensky, the Prime Minister and therefore chief representative of the Provisional Government, acted too hastily during the Kornilov Affair, misinterpreting Kornilov's intentions and making the Government seem against any sort of revolution, which went totally against what they were supposedly trying to achieve as an alternative to the Tsar.
Perhaps the most notable factor, though, was the rise of Lenin and the Bolsheviks. Following the Kornilov Affair, support for the Bolsheviks was at an all-time high, meaning they had a willing audience for a takeover - this was only strengthened by the fact that Lenin's April Theses, which promised 'power to the peasants', and the Bolshevik motto of 'Peace, Land and Bread' seemed to provide solutions to the issues the Provisional Government seemed incapable of handling. Indeed, that they recovered from the July Days was a testament to their popularity. Moreover, the takeover went smoothly owing to Trotsky's leadership, and was 'virtually bloodless', which only hastened the Provisional Government's downfall.
Overall, in conclusion, while weak leadership did indeed play a critical role in the fall of both political bodies in 1917, with the Tsar's poor decisions with the Dumas and the Government's haphazard composition, this was arguably all underpinned by greater issues, such as Rasputin and the defection of the armed forces in the Tsar's case, and the popularity of Lenin in the Provisional Government's.