The Only concept I've grasped out of all your input is that no one can make a "Tank" that Deviates from "Your Template". I asked for your Input because I had respect for the Riot build.
You say Running away from mobs and Not getting hit is better than Tumbling back and forth to keep them inthe same place? You just contradicted yourself. Running back and forth is FAR from Tumbling.....
Running = NO Boost to AC
Your Cannot Run Through a Mob. You must go around them... But you CAN Tumble Through Them.
By Holding down Block and Tumbling Back and Forth, I can Hold Aggro and Keep mobs confined to a very smal area for the Barbs and Rogues to beat on. THis is what your missing.