My first Marvel exposure to Fraction was actually really positive - I loved his Iron Fist title. Then he started getting involved in the big crossovers and unfortunately he cannot handle big crossovers. His plotting doesn't hold up, characters suddenly go hugely OOC to make up for it, and as soon as a female character is romantically involved with anyone she gets a personality transplant. His run on Iron Man also had these problems with the additional tendency to have rather...esoteric interpretations of previous canon material meaning that sometimes canon would be super important and sometimes he'd completely ignore huge parts of it and it was very inconsistent. His parts in the Everything Burns crossover were noticeably not up to the quality or coherency of Kieron Gillen's parts. This is why I think smaller titles suit him very well.