/u/CptBuck has actually written at length on this!
Most recently here: https://www.reddit.com/r/AskHistorians/comments/3n9nng/why_were_modern_arab_army_generally_incompetent/
This and other pieces in response to it seem to point to 3 general negatives to it.
Being that it is hilariously too broad for the actual evidence he brings into the discussion.
Doesn't gell well always with more thorough looks at the variety of Arab cultures, mil-civ relations, and larger systematic military trends to imply there is a single quantifiable "Arab" Military culture to examine.
That it also hasn't aged the best with more recent conflicts in the ME, and better examinations of the conflicts of the past, Soviet and US military doctrine, and even what makes a "good" military in context.