How do ancient sources both help and hinder our ability to view the roman face of battle?

What problems do historians confront when trying to understand Roman combat? How do ancient sources both help and hinder our ability to view the Roman face of battle?
In his article on Roman warfare, historian Philip Sabin points out that there is much about ancient combat that remains controversial or mysterious. Much of this is due to the fact that many of our written sources are mute or conflicted on information that might otherwise explain how Roman soldiers operated in battle.
Your job here is to examine the ancient sources about the battle of Cannae (and perhaps more general ancient sources about the Roman military) in light of Sabin’s and perhaps other modern historians’ treatment.
Note that, in every case, you are not simply giving a general description of what transpired at the battle, nor are you giving an overview of Sabin’s article. Rather, your task is to work within the theoretical frameworks that Sabin proposes, and to grapple with the ancient source materials within that context. If your findings indicate shortcomings in Sabin’s arguments, you should indicate what those are.
Be sure that you have focus for this assignment. To that end, your introduction should lay out very clearly what the problem is that you will be addressing, what your argument is, and how you will support it. Recall the training you received in GPAM.
Any and all sources from this unit’s selection of readings (or from other readings used thus far in class, if appropriate) can potentially be brought to bear on this assignment. Use of other secondary works is perfectly fine, but the bulk of your paper should concentrate on analysis of the ancient sources to respond to one of the above questions.
Note that excessive quoting from the sources is not advised, nor will it do your paper any good. Block quotes in a paper of this length are not appropriate, and dropped quotes will have negative grading implications. Remember the class discussion we had about effective quoting.