I dont really play pve too often but it seems to drop exotics somewhat often (compared to pvp) but i literally spend 95% of my time in crucible ive gotten to fabled and reset my rank 3 times in comp now (also have spent alot of time in IB and QP) and ive gotten a grand total of 0 exotic drops from crucible. 99% of the time if i get a drop from crucible i immediately dismantle it (because its always a trash legendary with even worse rolls) the loot pool just seems like its really bad in crucible, it doesn't reward you for the time you put into it.