Do you think it was because he focused on the first person narrative to support the points he described? There may be some gaps in the records, especially with the more gruesome stuff.
Basically, yes. He tried to unfold a battle through first hand accounts, rather than the opposite. When I write about a battle, I simply write about the battle and what happened. I prove that it happened in a certain way or add flair with first hand accounts or even secondary accounts. This was a clumsy work because he tried to tell a story via the first hand accounts rather than working them in smoothly. That is not to say that it was not interesting or entertaining, it just lacked fluidity. I really appreciate what he tried to do, but it just turned out to be a real pile, in my opinion.
Here is an example:
Just after the onset of the Battle of Issus, Alexander was faced with a perplexing problem. The river Issus was meandering, albeit shallow, and the slopes were very slick due to the week of rain that preceded the battle. The initial brilliant move of relocating his phalanxes after Darius made his first move was soon transformed into a blunder. The river meandered in such a way that it disallowed his infantry (notably the hypaspists from the Odrysian) to arrive at and cross the river at the same time. This created gaps, some large some small, throughout his moving line of infantry. Arrian claims the following: "Darius' Greek mercenaries attacked precisely at the point in the line where the gap was widest. There was a violent struggle. Darius' Greeks fought to thrust the Macedonians back into the water [...], while the Macedonians, in their turn [...], were determined not to forfeit the proud title of invincible, hitherto universally bestowed upon them. The fight was further embittered by the old racial rivalry of Greek and Macedonian. It was in this phase of the battle that Ptolemy, son of Seleucus, and about 121 Macedonians of distinction met a soldier's death."[Arrian,
Anabasis, 2.10.5-7.]