So for a competitive arena setup it seems the majority are 5 boxing shammys.

Why is the same setup not as effective for a 3v3 combo? Is it mostly because with the five shammy setup your shelling out enough burst damage to a single focused target to make them virtually ineffective or dead?

What would be some good arena strategy's with my current setup? I've gotten to the 1900's with my sl/sl lock (solo) and a disc priest and a frost specced mage seem like a good pairing despite the lack of melee is it possible