The Syrian crisis is well nigh the biggest blow to the current Iranian regime's prestige since it was established in 1979. It is now safe to argue that Iran is squandering the soft power it has been exercising among the various Muslim groups around the globe.
It is true that the new ruling party initially had problems with credibility, due to a lack of proper public diplomacy at the international level, the core of the Israeli state, in alliance with a powerful lobby in the US, chose to undermine it, using every opportunity to describe the AK Party as a dangerous one, with a hidden political agenda.
Day to day public diplomacy deals with particular groups, networks and individuals but it is also important to keep the big picture in mind. That big picture is not just the overall image of the country but the image of the preferred international order.