It’s too bad we don’t have data collection anymore because everyone is just going off personal feelings right now.
I just performed a manual search for a Mystic Forge deck that has won a tournament. I found one result way back on July 14 (the first weekend it was legal). Since then, very poor showing for the deck.
It can be concluded that in a meta that is prepared for it, KarnForge is not going to win the tournament and would be lucky to make top 8.
If the DCI doesn’t make changes it would be indicative of using real data to make a rational decision.