No it isn't.
This game is clearly heavily weighted if you have been playing it long enough.
When you play Iron Banner and get 6 class items in a row. Do the math on that. It's astronomical how ridiculous that is mathematically considering there's like 16 or 17 items.
Bungie knows Avalanche is terrible and they know Glacio has a killer roll.
I would guess it's more like 80-20, considering everyone I know is getting mainly Avalanches as well.