2016: two majors within 3 months. To consider an "era" you need at least 5 or 6 consecutive months of dominance like Astralis had this year.
2017, like I previously stated: No Major wins, upsetted by Heroic and Liquid, destroyed
2-0 by Astralis, had a roster change in between so their roster wasn't the same throughout the year.
Did NiP, Fnatic or Astralis changed their rosters during their eras? No
Did they won Majors? Yes
Did they get upsetted by shit teams? Probably, but most probably those were fluke performances from the other team like North's fluke performance on DH Stockholm.