A few years ago i read the three volums of the Byzantine history by J.J.Norwich. It is written in classical tradition, which means that he is looking at the people in charge, rather than looking out for structures and processes like the more recents aproches in historytelling would handle it.
One point was really striking. Norwich wrote that the Battle of Manzikert was neither so desastrous nor pivotal than one may think. The looses were heavy, but effordable and even the negotiated peace was more than moderate. They would have to cede a part of Armenia, something they just annexed a few years ago in a matter which made the most Armenians their enemies anyway. The Turks at the time of the engagement wanted actually to conquer Egypt to wipe out the Shiacaliphate and Alp Arslan was already at Aleppo when Romanos Diogenes marched in to Armenia. Even afterwards Egypt was the ultimate goal of the Turks until the Sucessor of Romanos broke the treaty and continued to harass the Turks in a situation were the Army needed recovering. Only than it was possible to take Anatolia.
Norwich states that the way to Manzikert was no random occasion, but a process started after the death of Basil II. In his opinion it was a fight between the military and the bureaucrats for power which resulted in that scenario. In the center was the kingmaker Michael Psellos, an incredible sophisticated man who is responsible for reetablishing the great university of Konstantinople once again, which made it a centre of study in the world. However his faction thought that a strong military is more dangerous, because of coup d'etats than a strong one which was able to defend the borders. In their theory it would be wise to have a strong, state controled economy which could pay enemies of and even more better use them as mercenaries in the future. Had Basil II the Bulgarslayer, who marked a highpoint of byzantine history, a strong greek army, his sucessors used more and more mercenaries and weaked that way the military influence within the empire. The result was a reduction of central power in military terms and an increase of power in economic questions. However without a strong imperial army, the military aristocracy like the Dukoi and Comnenoi started to build up their own private armies and eventually did what the Bureaucrats wanted to avoid. They took power. Isaac I. was an able general who could have reformed the state, but he failed, since he had only the support of the military and the bureaucrats especially, Michael Psellos, hated him for beeing an emperor they didn't put on the throne.
I've found Norwichs argumentation plausible and found it fascinating how strongly those people thought about state theories and how a government should work at it's best. Also that those people responsible were actually some of the most sophisticated minds of their time. You often have Andronicos Dukas as a simple traitor who fled in an opportunistic way in the "most pivotal battle", but their intentions are actually a lot more complex than that.
I would like to hear more voices on that matter and i would be also interested in further book suggestions. Norwich is great, but possibly also a bit outdated. Since i don't have time to read just "any" book on the matter i would prefer books someread already read and accounted as "great"