User blog comment:Kuopiofi/Saitama - Absolute or Supernatural?/@comment-4714517-20160906191402/@comment-24053170-20160908011238

In the series all the monsters/villians are rated by disaster rankings, the highest ranking so far is God which is described as a threat to the survival of humanity itself. Boros was not rated as such, he was ranked as about mid-tier Dragon at best.

Meaning that his ultimate attack was not a planet buster, because if he actually was then he would have been ranked as a God level disaster.

In fact so far nothing in the series has been ranked as a threat to humanity as a whole, if there was an actual God level threat in the manga then Saitama would likely be fighting for his life as well as everyone elses.

Though considering the authors problem with keeping the characters powers consistent, its hard to actually make an informed decision. So I am mostly going on what he has revealed so far.

Series like One Punch Man make it really hard to judge what the focus of the plot is actually going for. So for me, I am likely going to wait until the story actually ends before I make any permanent decisions.