I think that the First World War was the product of long-standing rivalries rather than a badly mismanaged Balkan Crisis because it was these rivalries that led to the Balkan Crisis. The Balkan Crisis may appear mismanaged because previous crises such as those in Morocco in 1905 and 1911 did not result in war.
In the July Crisis Austria-Hungary blamed Serbia for the assassination of Archduke Franz Ferdinand (the heir to the throne of the Austro-Hungarian Empire) despite not having conclusive proof. Austria-Hungary asked for German support to "eliminate Serbia as a power factor in the Balkans". Germany agreed, offering her full support for Austria- Hungary to start a war with Serbia, and this became known as the "blank cheque". Austria-Hungary and Germany could not have failed to realize the possibility of Russian intervention and a European war, suggesting to me that war was their objective. Austria-Hungary issued an impossible ultimatum to Serbia, which was likely to provoke a war.
Serbia was given only 48 hours to reply, so was forced to think quickly, or other countries would be mobilized and ready to attack. Serbia accepted all but one point of the ultimatum. Consequently war was announced. If given more time Serbia could have discussed the issue further in a conference. The British foreign minister, Grey suggested a conference, but this was rejected by Germany and Austria-Hungary, suggesting that they had deliberate aims for war during the Balkan Crisis, rather than the Balkan Crisis being mismanaged.
There was a long-standing rivalry between Austria-Hungary and Russia due to their interests in the Balkans. Russia saw her role as leading and supporting her fellow Slav peoples in the Balkans. This Pan-Slav concept provided an ideal excuse to interfere in the Balkans and to extend Russia's influence towards the Eastern Mediterranean.