For me the rule seems to be I get a much higher droprate the first time I kill a boss. Repeat runs have gotten me hardly anything (and most of that was duplicates!). RNG is RNG apperently. Still got 4/5 T15 in my first lockout though, so I can't complain.
They are higher, but of course still not 100%. Me and my brother's alt managed to gear upto 480+ very fast(2 weeks tops), while his wife finally hit ilvl 480 last lockout on her alt. It is definatly higher, but still rng.
I've gone through the entirety of ToT LFR and used all my bonus rolls, and I still didn't get dick squat but bags of gold. It happens.
I did finally get my tier legs last night though. 2-piece set bonus, so I was pretty happy there. I won a necklace from Tortos, then I used my bonus roll because I was hoping for a 1h axe he drops, and I ended up getting the same necklace twice. :|
Look at it this way. You're bored and want to kill some time with a dice game. The game is simple: every time you roll more than three, you get a point. The goal is to try and get as many points with 20 rolls.
Your first 20 rolls, you score 13 points. The second 20 rolls, you get 15. The third time you roll 20 times, you only get six points. Does this mean the dice changed? No, it just means you weren't lucky that time.
And that's exactly how RNG and loot rolls work, only slightly more complicated.
The good news is you can keep trying for loot on a boss as long as you have a greater coin to expend, and since its MSV you can easily get infinite coins.
1. Ask a friend who does not need 5.0 LFR gear if they have any incantations that that are taking up their inventory slots that they dont want. Then group up and kill the ghosts and have them pass on the chests. You will get 1-3 coins per kill. You can also offer to pay 100 gold per chest if they are reluctant to give them up or trade your unused incantations on your main with their alt that may need coins too. This requires you to log in as your main and they log in as an alt and you pass then log in as your alt and their main and they pass on chests.
2. Kill a rare on thunder isle or open a chest to get key to Lei Shen's treasure room. If you turn right, hop on the chest, hop on ledge and then open all chests along the wall until you work your way to the back and then repeat on the back lefthand side of the room back to the front you will pick up lots of chests with very little resistance and lots of coins. Watch out for the critter spiders in the back of the room as they will snare you. Just shoot them down.
You should be able to get 20 coins a week easily using this process (assuming you have some friends of course for incantations) and thats 20 extra chances at loot.
Well, in my opinion the item drop chance in the old LFRs (for normal and coin loot) is about 30%.
That means the chance to get nothing at 6 rolls (3 normal + 3 coins) is about 12%, whereas the chance to get an item from every boss and every coin roll is less than 1 per mille.
So getting nothing in a run happens to about every eigth person, meaning unlucky yes, improbable no.