https://en.wikipedia.org/wiki/Sykes%...icot_Agreement
Arab soldiers and commanders aren't incompetent historically speaking. But Arabs never fully transitioned into forming strong states and are largely tribal to this day. This lack of structure provided by a strong state, combined with the legacy of colonialism essentially ensures that Arab armies under perform and will continue doing so for the foreseeable future.
Words like Iraq, Libya, Saudi Arabia, or Yemen are largely irrelevant to the people living there.
The Iranians are an exception by having a strong unifying Persian identity combined with a lack of internal sectarian divisions (they are all Shia). This also seems to be a characteristic of the Kurds, although both groups share Arab military traditions and tactics.