Hi i am lex and i went over your log and the reality is rotationally speaking you do nothing wrong (at least nothing major, you execute right you use BF + SS stacks, you dont press BT etc. the only thing that is wrong is that you use Roar, the only reason on why we ever want to use Roar is that if we cant cast ANYNTHING BUT BT and Roar and in that case Roar takes prio but other than that its a wasted GCD which would be spent on RB)
your gear ... you are 710 ilvl which isnt super high but there are ppl with that ilvl who just have better gear i will make a list on whats slacking on your gear
- YOU DO NOT HAVE A WEAPON EMBELLISHMENT GET THAT ASAP on weapon we craft Ascension
- YOUR WRISTS HAVE THE WRONG EMBELLISHMENT we want "Writhing Armor Banding" same as the weapon get that stuff ASAP
- You dont have soul hunter boots which are a big dps inc as well even normal ones
- you have a green delve ring which has good stats but its super low ilvl
- your belt has the wrong effect equipped we want the stacking crit one (but maybe also the summery of gear might also just show the wrong one but i will call it out anyway) "Critical Chain" is the one we want
- You dont have a mythic weapon (which isnt your fault but I got lucky and had a mythic weapon week one and i was also in that ilvl braked which means you are also competing against ppl who have a mythic weapon)
-Are you sure you want 5x Haste mastery gems? i highly doubt that pls resim your gems
Now this explains your ILVL pars
but the reason why you are at 78 log overall is also very simple first of all your gear and second of all a 4:40 kill in week 4 i thin it is? my guild killed fracti this reset on a 2:50 pull its just that the kill is too long to log better I dont wan to bad mouth anyone but its just that there are a lot of ppl who could perform better on that kill if you get what i am saying
But yea thats acutally it, fix your gear and get into a grp with ppl who also have decent gear and you are fine your rotation is good 
If you have any more questions jsut ask me, you can dm me or @me here wherever you feel comfortable