He's been nerfed several times and he still wasn't automatic pick/ban even before. You seriously can't understand how broken Rumble is without seeing it yourself.
Yeah, this one was getting yelled at by his team for copying a pro build with no idea what he was doing. He defended himself with his "super high" 1500 elo.
If I were to start playing WoW again, it would be as a healer. No chance of starting as DPS or Tank again.