Very simply, how does a Quintuple Elemental Shaman setup ever lose in the 5v5 Arena (barring another team with the same setup)? I see no weakness. Please enlighten me on the downsides, before I invest the money.

With staggered Tremor Totems, staggered Magma Totems to break stealth, 5 healing streams (about 500 healing/2 secs), 4 Grounding Totems, and EM-NS-trinket CL, what group could possibly defeat you?

Personally, I would sit back, and always pop EM-NS CL on the first person to enter a radius of 36 yards around me. Now, it's 4v5, and the next person to come within my range is going to get 4x/5x Lightning Bolts followed with 4x/5x Earth Shocks in rapid succession. The rest will systematically die.

The only things that comes to mind is 1) multiple Shadowstep Rogues attacking in unison, or 2) a bubbled Paladin using HoJ and Repentance on 2 of your Shamans and the rest of his team entering the fray with mass AE and multiple AE fears to confuse you. Both would require perfect timing, but they could work. Even these, though, wouldn't work if you anticipated it.