The Produce type shows lost credibility after the voting manipulation... even if not, still it got jaded.
IOI was too short to benefit, Kep1er too late - the perfect beneficiaries were Iz*one.
Izone was also lucky in that they came when 3rd gen was already cemented, there were very few major 3.5 debuts.. - so they looked fresh.. but look at Kep1er's year,, 4th gen massive rivals are taking off. lots of competition.
Rest is about choice of songs, management strategies etc.,