Since they apparently haven't got much feedback about purple drop rates.
The set bonus drop rate is way too low and the green rate is way too high. At rank 40 I have 1 set bonus and 2 other purples (implant and ear). In the 30s I got green after green, 6 in a row, a blue then more greens. At this rate it will be impossible to get a full tier 1 set bonus before getting to rank 90 and starting on tier 2 gear. There should be no greens in the system. Nobody needs greens. Maybe if you didn't play KOTFE they would be an upgrade but guess what, blues would be an even bigger upgrade!