Well I have a low 20s warrior I was leveling on Mug'thol before I transferred Hierax over from Kargath. Here's how I did fights, and I had no issues at all with what I was doing.
I would charge into a group and pull 3-4 mobs at least. Then I would start Thunderclapping when it was available and cycling through the targets, keeping Rend up on all of them. I didn't really use Heroic Strike at all.
Worked well enough, but I kept my gear up at a decent level.
Here's my low level guy. For some reason it's not showing his talents but I went in Fury.
http://www.wowarmory.com/character-sheet.xml?r=Mug%27thol&n=Pariah