Tank Progression vs Dps Progression

Along with a blm friend of mine we decided to make a test as returning players on our progression starting from t5 to fcob. The results are rather dissapointing for me as war.
So one week after he managed to make it to t11 and i'm still stuck in t9. We played the same hours/day, we made our separate pf groups and yet he made it to t11 and he is able to farm t10 and t11.
For T9 i know the god damn fight perfectly well and yet i'm still getting my ass wiped...I always try to find people that know the fight at least up to p3 but in most cases things get messed up in p2. Fact is, in most fights i have to deal with crunches + tank swaps and dps have to deal with mechanics and sometimes i have to deal with both. So in the end should i blame my luck in finding groups?

realy don't understand how this is even issue.... you got shit groups case closed

Sounds like you just got bad groups and your friend just got lucky or bought a carry behind your back. Not that uncommon really in all mentioned cases.

I geared the majority of my DPS classes simply by running coil as WHM.

It really has nothing to do with which is easier or not. It's just, as a healer or tank, you get waaayyy more duty exposure.