Iranian revolutionary guards are at work with the Assads forces, now they are relying more on infantry than tanks
Syrian army is hopeless as is the rest of the Syrian militray, they made big mistakes in the early days of the demonstrations which has led to this situation but now Al Kuds and other Iranian elements are doing the business in Syria
They are well trained and have been doing this kind of warfare for decades, they are doing it again in Syria
Even If Assad goes the Iranians will outlast Assads regime, Iran has a back up force to reassure Hezbollah they are still in the game, if anyone can go guerrilla warfare it's the Iranain Basij units