In Iraq the Shia militias, many of them with Iranian advisors, are increasingly being seen as a problem by the new Iraqi government and Iraqis in general. The previous Maliki government had long worked closely with Iran but lost power because Maliki and his allies would not do anything about the corruption that is largely seen as the main reason ISIL made such rapid advances in 2014. Iraqis are discovering, as the anti-corruption efforts now accelerate, that a lot of that corruption, especially in the military, was encouraged, and sometimes paid for, by Iran. This has caused public opinion among the majority Shia Arabs in Iraq to turn against Iran. Another reason for that is the Iran supported (and often armed and paid) Shia militiamen are seen as fanatics and undisciplined who are mainly loyal to Iran. These Shia militiamen are largely motivated by revenge (for years of Islamic terrorist attacks on Shia civilians) and their Iranian advisors encourage that. A growing number of Iraqis see Iran as more of a threat than an ally.
If we had stayed in Iraq after 2011, I believe our military presence would have emboldened Iraqis to reject Iranian influence far more quickly.
UPDATE: More from Strategypage on Iraq. Despite my worries that we risk setbacks by giving our jihadi enemies time, there are good trends happening in Iraq, from fighting corruption to ISIL weakening to increased Iraqi awareness about the threat from Iran.