Au contraire...

If one feels the need to lay a claim against a person's performance then there HAS to be a baseline. This if the original poster wants his claims to be considered intellectually honest in presentation.

Now whether that baseline is absolute or relative is entirely up to the original poster.

Once one sets one's targets and handily demonstrates that Haejin either does not meet the absolute targets that one has set (and keeping in mind that a lack of others who actually do meet those targets obviously nullifies the argument), or performs worse than others who make predictions within the same space (whether due to his same claimed methodology or others), THEN there would be a valid case to call out Haejin's credibility in the matter.

Yes - its a little more work - but its a matter of formulating one's arguments correctly and in an adequately complete format.