What scared the Iranians was the skill levels of the Arab aircrew. These pilots had little or no combat experience but since mid-2014 many of them had been flying combat missions against ISIL (Islamic State in Iraq and the Levant) in Iraq and Syria and the air campaign in Yemen demonstrated these pilots, and their ground support facilities, could handle a “surge” (several sorties a day for weeks) and then thousands of more sorties over more than a year of operations.
Iran doesn't have much of an air force and doesn't have enough air defenses to really matter.
Oops.
