Mohammad Ayatollahi Tabaar explains how the Turkey's regional rise is torpedoing Iranian influence:

The Iranian government is aware of the ideological affinity between Iran's reformist opposition and the AKP [Turkey's ruling party]. Although they were born in diametrically opposed political systems, both strive to strike a balance between Islam and democracy. Iranian leaders fear that the AKP may inflict a similar damage to their legitimacy as the Iranian reform movement has. They acknowledge that the reformists, although defeated for now, managed to crack the heart of the establishment and bring many die-hard supporters of the regime to their side or neutralize them. Now, the AKP could create a similar legitimacy crisis for the Islamic government on a regional level, weakening Iran's soft power and undermining its popularity in the Muslim world.

Thomas P.M. Barnett notes another Turkish advantage over Iran: relative economic strength. Walter Russell Mead thinks the main beneficiary of the struggle between the two regional powers is the United States: