Tried a full tank team with 3 other gaffers and a random person (he's nunu). Some people were playing WAY too defensively (enemy chasing me when I close to dying, but they didn't come out from the tower to cc them; nor did they leave the tower to kill someone who is nearly dead). There is a line between playing defensively and never leaving your tower. There is no way we could of win if we just stay by the towers, it would give them full dragon and baron control. And if you are not leona, you need to be tanky dps not full tank, or else we would just be taking damage.
On a separate note, after looking at the stats, I am really surprise that Riot didn't include 'damage dealt to champions'. I assume that 'Damage Dealt' includes minion, neutral monsters, champion and turrets, but i don't really find this particularly interesting; it would be much better if it actually state the amount of damage dealt to enemy champions.