I believe that you should not generalize, as for some the Hype has lowered because maybe they theorized something that was not fulfilled to them, others are still generating Hype, perhaps because they are not so demanding, or perhaps because they prefer to wait for See what the author has in store and not want to force something to go according to an arbitrary expectation.
In my case I catalog in the last, they preferred not to generate theories as far as possible and if I believe them, I did not try to force them to be forced, I prefer to wait to see that the author introduces us and with that I get almost Everything pleases me, if it is true that there are plot holes, but man, I think a lot of them will be solving with time, I do not expect everything to be clarified at once because that takes the joke out of a long series.
With the Spriggan, I believe that some people expected the Spriggan to act as they have not performed characters in the works of Mashima or Nekketsu, or as quasi-invincible beings, and say that they fell the Hype fell because they were defeated but ... Were the Spriggan defeated by a Random? That I know not, not one has fallen before any character Random, is more, each victory cost a lot of effort to the characters, and I think if the complaint is because of the number of episodes for fights, I remind you that Mashima mechanics always Have been short fights, the fact of lasting more than two episodes in some characters indicates that they are really strong, so at least in my view each of them has fulfilled, to consider them "weak" would mean that those who faced them are Weak characters, since it is to demerit the one who defeated them.