During the early stages of WW1 the Russian campaigns in East Prussia and Austria were seen as having gotten off to a very favorable start. The Battle of Tannenburg quickly put a stop to that when Second Army was destroyed, First Army routed soon after, and Lvov abandoned to form a new line at Warsaw all before the end of 1914. Thus starting the trend of constant defeat and retreat after defeat that eventually led to revolution.
One major advantage the Germans had was that they cracked the Russian code book, or in some cases caught transmissions sent without using codes, allowing them to intercept the Russian mail and find undefended gaps in the Russian positions. What if the Russian armies in WW1 had access to a significantly better codebook (and actually provided enough code books for all the army leaders)? Could we possibly avert the Great Retreat, followed by the great defeat that killed the Russian Empire?